/* * Copyright 2013-2016 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the OpenSSL license (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy * in the file LICENSE in the source distribution or at * https://www.openssl.org/source/license.html */ /** Beware! * * Following wrapping modes were designed for AES but this implementation * allows you to use them for any 128 bit block cipher. */ #include "internal/cryptlib.h" #include /** RFC 3394 section 2.2.3.1 Default Initial Value */ static const unsigned char default_iv[] = { 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, }; /** RFC 5649 section 3 Alternative Initial Value 32-bit constant */ static const unsigned char default_aiv[] = { 0xA6, 0x59, 0x59, 0xA6 }; /** Input size limit: lower than maximum of standards but far larger than * anything that will be used in practice. */ #define CRYPTO128_WRAP_MAX (1UL << 31) /** Wrapping according to RFC 3394 section 2.2.1. * * @param[in] key Key value. * @param[in] iv IV value. Length = 8 bytes. NULL = use default_iv. * @param[in] in Plaintext as n 64-bit blocks, n >= 2. * @param[in] inlen Length of in. * @param[out] out Ciphertext. Minimal buffer length = (inlen + 8) bytes. * Input and output buffers can overlap if block function * supports that. * @param[in] block Block processing function. * @return 0 if inlen does not consist of n 64-bit blocks, n >= 2. * or if inlen > CRYPTO128_WRAP_MAX. * Output length if wrapping succeeded. */ size_t CRYPTO_128_wrap(void *key, const unsigned char *iv, unsigned char *out, const unsigned char *in, size_t inlen, block128_f block) { unsigned char *A, B[16], *R; size_t i, j, t; if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX)) return 0; A = B; t = 1; memmove(out + 8, in, inlen); if (!iv) iv = default_iv; memcpy(A, iv, 8); for (j = 0; j < 6; j++) { R = out + 8; for (i = 0; i < inlen; i += 8, t++, R += 8) { memcpy(B + 8, R, 8); block(B, B, key); A[7] ^= (unsigned char)(t & 0xff); if (t > 0xff) { A[6] ^= (unsigned char)((t >> 8) & 0xff); A[5] ^= (unsigned char)((t >> 16) & 0xff); A[4] ^= (unsigned char)((t >> 24) & 0xff); } memcpy(R, B + 8, 8); } } memcpy(out, A, 8); return inlen + 8; } /** Unwrapping according to RFC 3394 section 2.2.2 steps 1-2. * The IV check (step 3) is responsibility of the caller. * * @param[in] key Key value. * @param[out] iv Unchecked IV value. Minimal buffer length = 8 bytes. * @param[out] out Plaintext without IV. * Minimal buffer length = (inlen - 8) bytes. * Input and output buffers can overlap if block function * supports that. * @param[in] in Ciphertext as n 64-bit blocks. * @param[in] inlen Length of in. * @param[in] block Block processing function. * @return 0 if inlen is out of range [24, CRYPTO128_WRAP_MAX] * or if inlen is not a multiple of 8. * Output length otherwise. */ static size_t crypto_128_unwrap_raw(void *key, unsigned char *iv, unsigned char *out, const unsigned char *in, size_t inlen, block128_f block) { unsigned char *A, B[16], *R; size_t i, j, t; inlen -= 8; if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX)) return 0; A = B; t = 6 * (inlen >> 3); memcpy(A, in, 8); memmove(out, in + 8, inlen); for (j = 0; j < 6; j++) { R = out + inlen - 8; for (i = 0; i < inlen; i += 8, t--, R -= 8) { A[7] ^= (unsigned char)(t & 0xff); if (t > 0xff) { A[6] ^= (unsigned char)((t >> 8) & 0xff); A[5] ^= (unsigned char)((t >> 16) & 0xff); A[4] ^= (unsigned char)((t >> 24) & 0xff); } memcpy(B + 8, R, 8); block(B, B, key); memcpy(R, B + 8, 8); } } memcpy(iv, A, 8); return inlen; } /** Unwrapping according to RFC 3394 section 2.2.2, including the IV check. * The first block of plaintext has to match the supplied IV, otherwise an * error is returned. * * @param[in] key Key value. * @param[out] iv IV value to match against. Length = 8 bytes. * NULL = use default_iv. * @param[out] out Plaintext without IV. * Minimal buffer length = (inlen - 8) bytes. * Input and output buffers can overlap if block function * supports that. * @param[in] in Ciphertext as n 64-bit blocks. * @param[in] inlen Length of in. * @param[in] block Block processing function. * @return 0 if inlen is out of range [24, CRYPTO128_WRAP_MAX] * or if inlen is not a multiple of 8 * or if IV doesn't match expected value. * Output length otherwise. */ size_t CRYPTO_128_unwrap(void *key, const unsigned char *iv, unsigned char *out, const unsigned char *in, size_t inlen, block128_f block) { size_t ret; unsigned char got_iv[8]; ret = crypto_128_unwrap_raw(key, got_iv, out, in, inlen, block); if (ret == 0) return 0; if (!iv) iv = default_iv; if (CRYPTO_memcmp(got_iv, iv, 8)) { OPENSSL_cleanse(out, ret); return 0; } return ret; } /** Wrapping according to RFC 5649 section 4.1. * * @param[in] key Key value. * @param[in] icv (Non-standard) IV, 4 bytes. NULL = use default_aiv. * @param[out] out Ciphertext. Minimal buffer length = (inlen + 15) bytes. * Input and output buffers can overlap if block function * supports that. * @param[in] in Plaintext as n 64-bit blocks, n >= 2. * @param[in] inlen Length of in. * @param[in] block Block processing function. * @return 0 if inlen is out of range [1, CRYPTO128_WRAP_MAX]. * Output length if wrapping succeeded. */ size_t CRYPTO_128_wrap_pad(void *key, const unsigned char *icv, unsigned char *out, const unsigned char *in, size_t inlen, block128_f block) { /* n: number of 64-bit blocks in the padded key data * * If length of plain text is not a multiple of 8, pad the plain text octet * string on the right with octets of zeros, where final length is the * smallest multiple of 8 that is greater than length of plain text. * If length of plain text is a multiple of 8, then there is no padding. */ const size_t blocks_padded = (inlen + 7) / 8; /* CEILING(m/8) */ const size_t padded_len = blocks_padded * 8; const size_t padding_len = padded_len - inlen; /* RFC 5649 section 3: Alternative Initial Value */ unsigned char aiv[8]; int ret; /* Section 1: use 32-bit fixed field for plaintext octet length */ if (inlen == 0 || inlen >= CRYPTO128_WRAP_MAX) return 0; /* Section 3: Alternative Initial Value */ if (!icv) memcpy(aiv, default_aiv, 4); else memcpy(aiv, icv, 4); /* Standard doesn't mention this. */ aiv[4] = (inlen >> 24) & 0xFF; aiv[5] = (inlen >> 16) & 0xFF; aiv[6] = (inlen >> 8) & 0xFF; aiv[7] = inlen & 0xFF; if (padded_len == 8) { /* * Section 4.1 - special case in step 2: If the padded plaintext * contains exactly eight octets, then prepend the AIV and encrypt * the resulting 128-bit block using AES in ECB mode. */ memmove(out + 8, in, inlen); memcpy(out, aiv, 8); memset(out + 8 + inlen, 0, padding_len); block(out, out, key); ret = 16; /* AIV + padded input */ } else { memmove(out, in, inlen); memset(out + inlen, 0, padding_len); /* Section 4.1 step 1 */ ret = CRYPTO_128_wrap(key, aiv, out, out, padded_len, block); } return ret; } /** Unwrapping according to RFC 5649 section 4.2. * * @param[in] key Key value. * @param[in] icv (Non-standard) IV, 4 bytes. NULL = use default_aiv. * @param[out] out Plaintext. Minimal buffer length = (inlen - 8) bytes. * Input and output buffers can overlap if block function * supports that. * @param[in] in Ciphertext as n 64-bit blocks. * @param[in] inlen Length of in. * @param[in] block Block processing function. * @return 0 if inlen is out of range [16, CRYPTO128_WRAP_MAX], * or if inlen is not a multiple of 8 * or if IV and message length indicator doesn't match. * Output length if unwrapping succeeded and IV matches. */ size_t CRYPTO_128_unwrap_pad(void *key, const unsigned char *icv, unsigned char *out, const unsigned char *in, size_t inlen, block128_f block) { /* n: number of 64-bit blocks in the padded key data */ size_t n = inlen / 8 - 1; size_t padded_len; size_t padding_len; size_t ptext_len; /* RFC 5649 section 3: Alternative Initial Value */ unsigned char aiv[8]; static unsigned char zeros[8] = { 0x0 }; size_t ret; /* Section 4.2: Ciphertext length has to be (n+1) 64-bit blocks. */ if ((inlen & 0x7) != 0 || inlen < 16 || inlen >= CRYPTO128_WRAP_MAX) return 0; if (inlen == 16) { /* * Section 4.2 - special case in step 1: When n=1, the ciphertext * contains exactly two 64-bit blocks and they are decrypted as a * single AES block using AES in ECB mode: AIV | P[1] = DEC(K, C[0] | * C[1]) */ unsigned char buff[16]; block(in, buff, key); memcpy(aiv, buff, 8); /* Remove AIV */ memcpy(out, buff + 8, 8); padded_len = 8; OPENSSL_cleanse(buff, inlen); } else { padded_len = inlen - 8; ret = crypto_128_unwrap_raw(key, aiv, out, in, inlen, block); if (padded_len != ret) { OPENSSL_cleanse(out, inlen); return 0; } } /* * Section 3: AIV checks: Check that MSB(32,A) = A65959A6. Optionally a * user-supplied value can be used (even if standard doesn't mention * this). */ if ((!icv && CRYPTO_memcmp(aiv, default_aiv, 4)) || (icv && CRYPTO_memcmp(aiv, icv, 4))) { OPENSSL_cleanse(out, inlen); return 0; } /* * Check that 8*(n-1) < LSB(32,AIV) <= 8*n. If so, let ptext_len = * LSB(32,AIV). */ ptext_len = ((unsigned int)aiv[4] << 24) | ((unsigned int)aiv[5] << 16) | ((unsigned int)aiv[6] << 8) | (unsigned int)aiv[7]; if (8 * (n - 1) >= ptext_len || ptext_len > 8 * n) { OPENSSL_cleanse(out, inlen); return 0; } /* * Check that the rightmost padding_len octets of the output data are * zero. */ padding_len = padded_len - ptext_len; if (CRYPTO_memcmp(out + ptext_len, zeros, padding_len) != 0) { OPENSSL_cleanse(out, inlen); return 0; } /* Section 4.2 step 3: Remove padding */ return ptext_len; }