/* crypto/modes/wrap128.c */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
* project.
+ * Mode with padding contributed by Petr Spacek (pspacek@redhat.com).
*/
/* ====================================================================
* Copyright (c) 2013 The OpenSSL Project. All rights reserved.
* ====================================================================
*/
+/** Beware!
+ *
+ * Following wrapping modes were designed for AES but this implementation
+ * allows you to use them for any 128 bit block cipher.
+ */
+
#include "cryptlib.h"
#include <openssl/modes.h>
+/** RFC 3394 section 2.2.3.1 Default Initial Value */
static const unsigned char default_iv[] = {
0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6,
};
-/* Input size limit: lower than maximum of standards but far larger than
- * anything that will be used in practice.
+
+/** 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 Plain text as n 64-bit blocks, n >= 2.
+ * @param[in] inlen Length of in.
+ * @param[out] out Cipher text. 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 < 8) || (inlen > CRYPTO128_WRAP_MAX))
+ if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
return 0;
A = B;
t = 1;
- memcpy(out + 8, in, inlen);
+ memmove(out + 8, in, inlen);
if (!iv)
iv = default_iv;
return inlen + 8;
}
-size_t CRYPTO_128_unwrap(void *key, const unsigned char *iv,
- unsigned char *out,
- const unsigned char *in, size_t inlen, block128_f block)
+
+/** Unwrapping according to RFC 3394 section 2.2.2 steps 1-2.
+ * 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 Plain text without IV.
+ * Minimal buffer length = (inlen - 8) bytes.
+ * Input and output buffers can overlap if block function
+ * supports that.
+ * @param[in] in Ciphertext text 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 multiply 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;
A = B;
t = 6 * (inlen >> 3);
memcpy(A, in, 8);
- memcpy(out, in + 8, inlen);
+ memmove(out, in + 8, inlen);
for (j = 0; j < 6; j++)
{
R = out + inlen - 8;
memcpy(R, B + 8, 8);
}
}
+ memcpy(iv, A, 8);
+ return inlen;
+ }
+
+/** Unwrapping according to RFC 3394 section 2.2.2 including IV check.
+ * First block of plain text have to match supplied IV otherwise an error is
+ * returned.
+ *
+ * @param[in] key Key value.
+ * @param[out] iv Unchecked IV value. Minimal buffer length = 8 bytes.
+ * @param[out] out Plain text without IV.
+ * Minimal buffer length = (inlen - 8) bytes.
+ * Input and output buffers can overlap if block function
+ * supports that.
+ * @param[in] in Ciphertext text 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 multiply 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 != inlen)
+ return ret;
+
if (!iv)
iv = default_iv;
- if (memcmp(A, iv, 8))
+ if (CRYPTO_memcmp(out, iv, 8))
{
OPENSSL_cleanse(out, inlen);
return 0;
}
return inlen;
}
+
+/** 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 Cipher text. Minimal buffer length = (inlen + 15) bytes.
+ * Input and output buffers can overlap if block function
+ * supports that.
+ * @param[in] in Plain text 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 */
+ const size_t blocks_padded = (inlen + 8) / 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 Plain text. Minimal buffer length = inlen bytes.
+ * Input and output buffers can overlap if block function
+ * supports that.
+ * @param[in] in Ciphertext text 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 multiply 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: Cipher text length has to be (n+1) 64-bit blocks. */
+ if ((inlen & 0x7) != 0 || inlen < 16 || inlen >= CRYPTO128_WRAP_MAX)
+ return 0;
+
+ memmove(out, in, inlen);
+ 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])
+ */
+ block(out, out, key);
+ memcpy(aiv, out, 8);
+ /* Remove AIV */
+ memmove(out, out + 8, 8);
+ padded_len = 8;
+ }
+ else
+ {
+ padded_len = inlen - 8;
+ ret = crypto_128_unwrap_raw(key, aiv, out, out, 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 = (aiv[4] << 24) | (aiv[5] << 16) | (aiv[6] << 8) | 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;
+ }
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