525 lines
14 KiB
C
525 lines
14 KiB
C
/*
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* Privacy Enhanced Mail (PEM) decoding
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
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*/
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#include "common.h"
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#if defined(MBEDTLS_PEM_PARSE_C) || defined(MBEDTLS_PEM_WRITE_C)
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#include "mbedtls/pem.h"
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#include "mbedtls/base64.h"
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#include "mbedtls/des.h"
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#include "mbedtls/aes.h"
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#include "mbedtls/md.h"
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#include "mbedtls/cipher.h"
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#include "mbedtls/platform_util.h"
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#include "mbedtls/error.h"
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#include <string.h>
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#include "mbedtls/platform.h"
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#if defined(MBEDTLS_USE_PSA_CRYPTO)
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#include "psa/crypto.h"
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#endif
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#if defined(MBEDTLS_MD_CAN_MD5) && \
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defined(MBEDTLS_CIPHER_MODE_CBC) && \
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(defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C))
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#define PEM_RFC1421
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#endif /* MBEDTLS_MD_CAN_MD5 &&
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MBEDTLS_CIPHER_MODE_CBC &&
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( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
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#if defined(MBEDTLS_PEM_PARSE_C)
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void mbedtls_pem_init(mbedtls_pem_context *ctx)
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{
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memset(ctx, 0, sizeof(mbedtls_pem_context));
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}
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#if defined(PEM_RFC1421)
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/*
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* Read a 16-byte hex string and convert it to binary
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*/
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static int pem_get_iv(const unsigned char *s, unsigned char *iv,
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size_t iv_len)
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{
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size_t i, j, k;
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memset(iv, 0, iv_len);
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for (i = 0; i < iv_len * 2; i++, s++) {
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if (*s >= '0' && *s <= '9') {
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j = *s - '0';
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} else
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if (*s >= 'A' && *s <= 'F') {
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j = *s - '7';
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} else
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if (*s >= 'a' && *s <= 'f') {
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j = *s - 'W';
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} else {
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return MBEDTLS_ERR_PEM_INVALID_ENC_IV;
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}
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k = ((i & 1) != 0) ? j : j << 4;
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iv[i >> 1] = (unsigned char) (iv[i >> 1] | k);
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}
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return 0;
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}
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static int pem_pbkdf1(unsigned char *key, size_t keylen,
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unsigned char *iv,
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const unsigned char *pwd, size_t pwdlen)
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{
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mbedtls_md_context_t md5_ctx;
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const mbedtls_md_info_t *md5_info;
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unsigned char md5sum[16];
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size_t use_len;
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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mbedtls_md_init(&md5_ctx);
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/* Prepare the context. (setup() errors gracefully on NULL info.) */
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md5_info = mbedtls_md_info_from_type(MBEDTLS_MD_MD5);
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if ((ret = mbedtls_md_setup(&md5_ctx, md5_info, 0)) != 0) {
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goto exit;
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}
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/*
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* key[ 0..15] = MD5(pwd || IV)
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*/
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if ((ret = mbedtls_md_starts(&md5_ctx)) != 0) {
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goto exit;
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}
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if ((ret = mbedtls_md_update(&md5_ctx, pwd, pwdlen)) != 0) {
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goto exit;
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}
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if ((ret = mbedtls_md_update(&md5_ctx, iv, 8)) != 0) {
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goto exit;
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}
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if ((ret = mbedtls_md_finish(&md5_ctx, md5sum)) != 0) {
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goto exit;
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}
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if (keylen <= 16) {
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memcpy(key, md5sum, keylen);
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goto exit;
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}
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memcpy(key, md5sum, 16);
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/*
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* key[16..23] = MD5(key[ 0..15] || pwd || IV])
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*/
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if ((ret = mbedtls_md_starts(&md5_ctx)) != 0) {
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goto exit;
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}
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if ((ret = mbedtls_md_update(&md5_ctx, md5sum, 16)) != 0) {
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goto exit;
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}
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if ((ret = mbedtls_md_update(&md5_ctx, pwd, pwdlen)) != 0) {
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goto exit;
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}
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if ((ret = mbedtls_md_update(&md5_ctx, iv, 8)) != 0) {
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goto exit;
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}
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if ((ret = mbedtls_md_finish(&md5_ctx, md5sum)) != 0) {
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goto exit;
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}
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use_len = 16;
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if (keylen < 32) {
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use_len = keylen - 16;
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}
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memcpy(key + 16, md5sum, use_len);
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exit:
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mbedtls_md_free(&md5_ctx);
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mbedtls_platform_zeroize(md5sum, 16);
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return ret;
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}
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#if defined(MBEDTLS_DES_C)
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/*
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* Decrypt with DES-CBC, using PBKDF1 for key derivation
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*/
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static int pem_des_decrypt(unsigned char des_iv[8],
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unsigned char *buf, size_t buflen,
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const unsigned char *pwd, size_t pwdlen)
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{
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mbedtls_des_context des_ctx;
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unsigned char des_key[8];
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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mbedtls_des_init(&des_ctx);
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if ((ret = pem_pbkdf1(des_key, 8, des_iv, pwd, pwdlen)) != 0) {
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goto exit;
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}
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if ((ret = mbedtls_des_setkey_dec(&des_ctx, des_key)) != 0) {
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goto exit;
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}
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ret = mbedtls_des_crypt_cbc(&des_ctx, MBEDTLS_DES_DECRYPT, buflen,
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des_iv, buf, buf);
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exit:
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mbedtls_des_free(&des_ctx);
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mbedtls_platform_zeroize(des_key, 8);
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return ret;
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}
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/*
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* Decrypt with 3DES-CBC, using PBKDF1 for key derivation
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*/
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static int pem_des3_decrypt(unsigned char des3_iv[8],
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unsigned char *buf, size_t buflen,
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const unsigned char *pwd, size_t pwdlen)
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{
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mbedtls_des3_context des3_ctx;
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unsigned char des3_key[24];
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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mbedtls_des3_init(&des3_ctx);
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if ((ret = pem_pbkdf1(des3_key, 24, des3_iv, pwd, pwdlen)) != 0) {
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goto exit;
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}
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if ((ret = mbedtls_des3_set3key_dec(&des3_ctx, des3_key)) != 0) {
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goto exit;
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}
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ret = mbedtls_des3_crypt_cbc(&des3_ctx, MBEDTLS_DES_DECRYPT, buflen,
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des3_iv, buf, buf);
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exit:
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mbedtls_des3_free(&des3_ctx);
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mbedtls_platform_zeroize(des3_key, 24);
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return ret;
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}
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#endif /* MBEDTLS_DES_C */
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#if defined(MBEDTLS_AES_C)
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/*
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* Decrypt with AES-XXX-CBC, using PBKDF1 for key derivation
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*/
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static int pem_aes_decrypt(unsigned char aes_iv[16], unsigned int keylen,
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unsigned char *buf, size_t buflen,
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const unsigned char *pwd, size_t pwdlen)
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{
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mbedtls_aes_context aes_ctx;
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unsigned char aes_key[32];
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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mbedtls_aes_init(&aes_ctx);
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if ((ret = pem_pbkdf1(aes_key, keylen, aes_iv, pwd, pwdlen)) != 0) {
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goto exit;
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}
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if ((ret = mbedtls_aes_setkey_dec(&aes_ctx, aes_key, keylen * 8)) != 0) {
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goto exit;
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}
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ret = mbedtls_aes_crypt_cbc(&aes_ctx, MBEDTLS_AES_DECRYPT, buflen,
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aes_iv, buf, buf);
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exit:
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mbedtls_aes_free(&aes_ctx);
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mbedtls_platform_zeroize(aes_key, keylen);
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return ret;
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}
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#endif /* MBEDTLS_AES_C */
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#endif /* PEM_RFC1421 */
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int mbedtls_pem_read_buffer(mbedtls_pem_context *ctx, const char *header, const char *footer,
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const unsigned char *data, const unsigned char *pwd,
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size_t pwdlen, size_t *use_len)
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{
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int ret, enc;
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size_t len;
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unsigned char *buf;
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const unsigned char *s1, *s2, *end;
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#if defined(PEM_RFC1421)
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unsigned char pem_iv[16];
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mbedtls_cipher_type_t enc_alg = MBEDTLS_CIPHER_NONE;
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#else
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((void) pwd);
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((void) pwdlen);
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#endif /* PEM_RFC1421 */
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if (ctx == NULL) {
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return MBEDTLS_ERR_PEM_BAD_INPUT_DATA;
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}
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s1 = (unsigned char *) strstr((const char *) data, header);
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if (s1 == NULL) {
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return MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT;
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}
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s2 = (unsigned char *) strstr((const char *) data, footer);
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if (s2 == NULL || s2 <= s1) {
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return MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT;
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}
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s1 += strlen(header);
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if (*s1 == ' ') {
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s1++;
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}
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if (*s1 == '\r') {
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s1++;
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}
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if (*s1 == '\n') {
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s1++;
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} else {
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return MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT;
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}
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end = s2;
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end += strlen(footer);
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if (*end == ' ') {
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end++;
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}
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if (*end == '\r') {
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end++;
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}
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if (*end == '\n') {
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end++;
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}
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*use_len = end - data;
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enc = 0;
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if (s2 - s1 >= 22 && memcmp(s1, "Proc-Type: 4,ENCRYPTED", 22) == 0) {
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#if defined(PEM_RFC1421)
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enc++;
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s1 += 22;
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if (*s1 == '\r') {
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s1++;
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}
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if (*s1 == '\n') {
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s1++;
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} else {
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return MBEDTLS_ERR_PEM_INVALID_DATA;
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}
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#if defined(MBEDTLS_DES_C)
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if (s2 - s1 >= 23 && memcmp(s1, "DEK-Info: DES-EDE3-CBC,", 23) == 0) {
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enc_alg = MBEDTLS_CIPHER_DES_EDE3_CBC;
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s1 += 23;
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if (s2 - s1 < 16 || pem_get_iv(s1, pem_iv, 8) != 0) {
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return MBEDTLS_ERR_PEM_INVALID_ENC_IV;
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}
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s1 += 16;
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} else if (s2 - s1 >= 18 && memcmp(s1, "DEK-Info: DES-CBC,", 18) == 0) {
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enc_alg = MBEDTLS_CIPHER_DES_CBC;
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s1 += 18;
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if (s2 - s1 < 16 || pem_get_iv(s1, pem_iv, 8) != 0) {
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return MBEDTLS_ERR_PEM_INVALID_ENC_IV;
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}
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s1 += 16;
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}
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#endif /* MBEDTLS_DES_C */
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#if defined(MBEDTLS_AES_C)
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if (s2 - s1 >= 14 && memcmp(s1, "DEK-Info: AES-", 14) == 0) {
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if (s2 - s1 < 22) {
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return MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG;
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} else if (memcmp(s1, "DEK-Info: AES-128-CBC,", 22) == 0) {
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enc_alg = MBEDTLS_CIPHER_AES_128_CBC;
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} else if (memcmp(s1, "DEK-Info: AES-192-CBC,", 22) == 0) {
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enc_alg = MBEDTLS_CIPHER_AES_192_CBC;
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} else if (memcmp(s1, "DEK-Info: AES-256-CBC,", 22) == 0) {
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enc_alg = MBEDTLS_CIPHER_AES_256_CBC;
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} else {
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return MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG;
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}
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s1 += 22;
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if (s2 - s1 < 32 || pem_get_iv(s1, pem_iv, 16) != 0) {
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return MBEDTLS_ERR_PEM_INVALID_ENC_IV;
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}
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s1 += 32;
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}
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#endif /* MBEDTLS_AES_C */
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if (enc_alg == MBEDTLS_CIPHER_NONE) {
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return MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG;
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}
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if (*s1 == '\r') {
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s1++;
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}
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if (*s1 == '\n') {
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s1++;
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} else {
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return MBEDTLS_ERR_PEM_INVALID_DATA;
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}
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#else
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return MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE;
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#endif /* PEM_RFC1421 */
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}
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if (s1 >= s2) {
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return MBEDTLS_ERR_PEM_INVALID_DATA;
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}
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ret = mbedtls_base64_decode(NULL, 0, &len, s1, s2 - s1);
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if (ret == MBEDTLS_ERR_BASE64_INVALID_CHARACTER) {
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return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PEM_INVALID_DATA, ret);
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}
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if ((buf = mbedtls_calloc(1, len)) == NULL) {
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return MBEDTLS_ERR_PEM_ALLOC_FAILED;
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}
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if ((ret = mbedtls_base64_decode(buf, len, &len, s1, s2 - s1)) != 0) {
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mbedtls_zeroize_and_free(buf, len);
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return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PEM_INVALID_DATA, ret);
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}
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if (enc != 0) {
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#if defined(PEM_RFC1421)
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if (pwd == NULL) {
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mbedtls_zeroize_and_free(buf, len);
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return MBEDTLS_ERR_PEM_PASSWORD_REQUIRED;
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}
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ret = 0;
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#if defined(MBEDTLS_DES_C)
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if (enc_alg == MBEDTLS_CIPHER_DES_EDE3_CBC) {
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ret = pem_des3_decrypt(pem_iv, buf, len, pwd, pwdlen);
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} else if (enc_alg == MBEDTLS_CIPHER_DES_CBC) {
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ret = pem_des_decrypt(pem_iv, buf, len, pwd, pwdlen);
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}
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#endif /* MBEDTLS_DES_C */
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#if defined(MBEDTLS_AES_C)
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if (enc_alg == MBEDTLS_CIPHER_AES_128_CBC) {
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ret = pem_aes_decrypt(pem_iv, 16, buf, len, pwd, pwdlen);
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} else if (enc_alg == MBEDTLS_CIPHER_AES_192_CBC) {
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ret = pem_aes_decrypt(pem_iv, 24, buf, len, pwd, pwdlen);
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} else if (enc_alg == MBEDTLS_CIPHER_AES_256_CBC) {
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ret = pem_aes_decrypt(pem_iv, 32, buf, len, pwd, pwdlen);
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}
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#endif /* MBEDTLS_AES_C */
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if (ret != 0) {
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mbedtls_free(buf);
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return ret;
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}
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/*
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* The result will be ASN.1 starting with a SEQUENCE tag, with 1 to 3
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* length bytes (allow 4 to be sure) in all known use cases.
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*
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* Use that as a heuristic to try to detect password mismatches.
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*/
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if (len <= 2 || buf[0] != 0x30 || buf[1] > 0x83) {
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mbedtls_zeroize_and_free(buf, len);
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return MBEDTLS_ERR_PEM_PASSWORD_MISMATCH;
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}
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#else
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mbedtls_zeroize_and_free(buf, len);
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return MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE;
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#endif /* PEM_RFC1421 */
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}
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ctx->buf = buf;
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ctx->buflen = len;
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return 0;
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}
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void mbedtls_pem_free(mbedtls_pem_context *ctx)
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{
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if (ctx->buf != NULL) {
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mbedtls_zeroize_and_free(ctx->buf, ctx->buflen);
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}
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mbedtls_free(ctx->info);
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mbedtls_platform_zeroize(ctx, sizeof(mbedtls_pem_context));
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}
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#endif /* MBEDTLS_PEM_PARSE_C */
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#if defined(MBEDTLS_PEM_WRITE_C)
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int mbedtls_pem_write_buffer(const char *header, const char *footer,
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const unsigned char *der_data, size_t der_len,
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unsigned char *buf, size_t buf_len, size_t *olen)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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unsigned char *encode_buf = NULL, *c, *p = buf;
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size_t len = 0, use_len, add_len = 0;
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mbedtls_base64_encode(NULL, 0, &use_len, der_data, der_len);
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/* Newlines are appended to the end of both header and footer, so we
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* account for an extra +2. */
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add_len = strlen(header) + strlen(footer) + 2 + \
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(((use_len > 2) ? (use_len - 2) : 0) / 64) + 1;
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if (use_len + add_len > buf_len) {
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*olen = use_len + add_len;
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return MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL;
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}
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if (use_len != 0 &&
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((encode_buf = mbedtls_calloc(1, use_len)) == NULL)) {
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return MBEDTLS_ERR_PEM_ALLOC_FAILED;
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}
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if ((ret = mbedtls_base64_encode(encode_buf, use_len, &use_len, der_data,
|
|
der_len)) != 0) {
|
|
mbedtls_free(encode_buf);
|
|
return ret;
|
|
}
|
|
|
|
memcpy(p, header, strlen(header));
|
|
p += strlen(header);
|
|
*p++ = '\n';
|
|
c = encode_buf;
|
|
|
|
while (use_len) {
|
|
len = (use_len > 64) ? 64 : use_len;
|
|
memcpy(p, c, len);
|
|
use_len -= len;
|
|
p += len;
|
|
c += len;
|
|
*p++ = '\n';
|
|
}
|
|
|
|
memcpy(p, footer, strlen(footer));
|
|
p += strlen(footer);
|
|
*p++ = '\n';
|
|
|
|
*p++ = '\0';
|
|
*olen = p - buf;
|
|
|
|
/* Clean any remaining data previously written to the buffer */
|
|
memset(buf + *olen, 0, buf_len - *olen);
|
|
|
|
mbedtls_free(encode_buf);
|
|
return 0;
|
|
}
|
|
#endif /* MBEDTLS_PEM_WRITE_C */
|
|
#endif /* MBEDTLS_PEM_PARSE_C || MBEDTLS_PEM_WRITE_C */
|