Initial *very* experimental EVP support for AES-GCM. Note: probably very
broken and subject to change.
This commit is contained in:
Dr. Stephen Henson
parent
fd3dbc1dbf
commit
bdaa54155c
9
CHANGES
9
CHANGES
@ -4,6 +4,15 @@
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Changes between 1.0.1 and 1.1.0 [xx XXX xxxx]
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*) Initial, experimental EVP support for AES-GCM. AAD can be input by
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setting output buffer to NULL. The *Final function must be
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called although it will not retrieve any additional data. The tag
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can be set or retrieved with a ctrl. The IV length is by default 12
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bytes (96 bits) but can be set to an alternative value. If the IV
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length exceeds the maximum IV length (currently 16 bytes) it cannot be
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set before the key.
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[Steve Henson]
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*) New flag in ciphers: EVP_CIPH_FLAG_CUSTOM_CIPHER. This means the
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underlying do_cipher function handles all cipher semantics itself
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including padding and finalisation. This is useful if (for example)
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@ -57,8 +57,8 @@
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#include <string.h>
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#include <assert.h>
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#include <openssl/aes.h>
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#include <openssl/modes.h>
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#include "evp_locl.h"
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#include <openssl/modes.h>
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static int aes_init_key(EVP_CIPHER_CTX *ctx, const unsigned char *key,
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const unsigned char *iv, int enc);
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@ -187,4 +187,212 @@ static int aes_init_key(EVP_CIPHER_CTX *ctx, const unsigned char *key,
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return 1;
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}
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typedef struct
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{
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/* AES key schedule to use */
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AES_KEY ks;
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/* Set if key initialised */
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int key_set;
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/* Set if an iv is set */
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int iv_set;
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/* Pointer to GCM128_CTX: FIXME actual structure later */
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GCM128_CONTEXT *gcm;
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/* IV length */
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int ivlen;
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/* Tag to verify */
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unsigned char tag[16];
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int taglen;
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} EVP_AES_GCM_CTX;
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static int aes_gcm_cleanup(EVP_CIPHER_CTX *c)
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{
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EVP_AES_GCM_CTX *gctx = c->cipher_data;
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if (gctx->gcm)
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CRYPTO_gcm128_release(gctx->gcm);
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return 1;
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}
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static int aes_gcm_ctrl(EVP_CIPHER_CTX *c, int type, int arg, void *ptr)
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{
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EVP_AES_GCM_CTX *gctx = c->cipher_data;
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switch (type)
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{
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case EVP_CTRL_INIT:
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gctx->gcm = NULL;
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gctx->key_set = 0;
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gctx->iv_set = 0;
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gctx->ivlen = c->cipher->iv_len;
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gctx->taglen = -1;
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return 1;
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case EVP_CTRL_GCM_SET_IVLEN:
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if (arg <= 0)
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return 0;
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gctx->ivlen = arg;
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return 1;
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case EVP_CTRL_GCM_SET_TAG:
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if (arg <= 0 || arg > 16 || c->encrypt)
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return 0;
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memcpy(gctx->tag, ptr, arg);
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gctx->taglen = arg;
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return 1;
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case EVP_CTRL_GCM_GET_TAG:
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if (arg <= 0 || arg > 16 || !c->encrypt || gctx->taglen < 0)
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return 0;
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memcpy(ptr, gctx->tag, arg);
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return 1;
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default:
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return -1;
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}
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}
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static int aes_gcm_init_key(EVP_CIPHER_CTX *ctx, const unsigned char *key,
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const unsigned char *iv, int enc)
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{
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EVP_AES_GCM_CTX *gctx = ctx->cipher_data;
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if (!iv && !key)
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return 1;
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if (key)
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{
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AES_set_encrypt_key(key, ctx->key_len * 8, &gctx->ks);
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if (!gctx->gcm)
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{
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gctx->gcm =
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CRYPTO_gcm128_new(&gctx->ks, (block128_f)AES_encrypt);
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if (!gctx->gcm)
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return 0;
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}
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else
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CRYPTO_gcm128_init(gctx->gcm, &gctx->ks, (block128_f)AES_encrypt);
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/* If we have an iv can set it directly, otherwise use
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* saved IV.
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*/
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if (iv == NULL && gctx->iv_set)
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iv = ctx->iv;
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if (iv)
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{
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CRYPTO_gcm128_setiv(gctx->gcm, iv, gctx->ivlen);
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gctx->iv_set = 1;
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}
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gctx->key_set = 1;
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}
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else
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{
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/* If key set use IV, otherwise copy */
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if (gctx->key_set)
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CRYPTO_gcm128_setiv(gctx->gcm, iv, gctx->ivlen);
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else
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{
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/* If IV is too large for EVP_CIPHER_CTX buffer
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* return an error. This can be avoided by either
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* setting the key first or key and iv simultaneously.
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*/
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if (gctx->ivlen > EVP_MAX_IV_LENGTH)
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return 0;
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memcpy(ctx->iv, iv, gctx->ivlen);
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}
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gctx->iv_set = 1;
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}
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return 1;
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}
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static int aes_gcm(EVP_CIPHER_CTX *ctx, unsigned char *out,
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const unsigned char *in, size_t len)
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{
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EVP_AES_GCM_CTX *gctx = ctx->cipher_data;
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/* If not set up, return error */
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if (!gctx->iv_set && !gctx->key_set)
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return -1;
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if (!ctx->encrypt && gctx->taglen < 0)
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return -1;
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if (in)
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{
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if (out == NULL)
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CRYPTO_gcm128_aad(gctx->gcm, in, len);
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else if (ctx->encrypt)
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CRYPTO_gcm128_encrypt(gctx->gcm, in, out, len);
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else
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CRYPTO_gcm128_decrypt(gctx->gcm, in, out, len);
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return len;
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}
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else
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{
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if (!ctx->encrypt)
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{
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if (CRYPTO_gcm128_finish(gctx->gcm,
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gctx->tag, gctx->taglen) != 0)
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return -1;
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gctx->iv_set = 0;
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return 0;
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}
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CRYPTO_gcm128_tag(gctx->gcm, gctx->tag, 16);
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gctx->taglen = 16;
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/* Don't reuse the IV */
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gctx->iv_set = 0;
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return 0;
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}
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}
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static const EVP_CIPHER aes_128_gcm_cipher=
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{
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NID_aes_128_gcm,1,16,12,
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EVP_CIPH_GCM_MODE|EVP_CIPH_FLAG_FIPS|EVP_CIPH_FLAG_DEFAULT_ASN1
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| EVP_CIPH_CUSTOM_IV | EVP_CIPH_FLAG_CUSTOM_CIPHER
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| EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CTRL_INIT,
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aes_gcm_init_key,
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aes_gcm,
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aes_gcm_cleanup,
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sizeof(EVP_AES_GCM_CTX),
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NULL,
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NULL,
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aes_gcm_ctrl,
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NULL
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};
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const EVP_CIPHER *EVP_aes_128_gcm (void)
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{ return &aes_128_gcm_cipher; }
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static const EVP_CIPHER aes_192_gcm_cipher=
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{
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NID_aes_128_gcm,1,24,12,
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EVP_CIPH_GCM_MODE|EVP_CIPH_FLAG_FIPS|EVP_CIPH_FLAG_DEFAULT_ASN1
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| EVP_CIPH_CUSTOM_IV | EVP_CIPH_FLAG_CUSTOM_CIPHER
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| EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CTRL_INIT,
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aes_gcm_init_key,
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aes_gcm,
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aes_gcm_cleanup,
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sizeof(EVP_AES_GCM_CTX),
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NULL,
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NULL,
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aes_gcm_ctrl,
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NULL
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};
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const EVP_CIPHER *EVP_aes_192_gcm (void)
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{ return &aes_192_gcm_cipher; }
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static const EVP_CIPHER aes_256_gcm_cipher=
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{
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NID_aes_128_gcm,1,32,12,
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EVP_CIPH_GCM_MODE|EVP_CIPH_FLAG_FIPS|EVP_CIPH_FLAG_DEFAULT_ASN1
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| EVP_CIPH_CUSTOM_IV | EVP_CIPH_FLAG_CUSTOM_CIPHER
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| EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CTRL_INIT,
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aes_gcm_init_key,
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aes_gcm,
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aes_gcm_cleanup,
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sizeof(EVP_AES_GCM_CTX),
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NULL,
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NULL,
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aes_gcm_ctrl,
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NULL
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};
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const EVP_CIPHER *EVP_aes_256_gcm (void)
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{ return &aes_256_gcm_cipher; }
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#endif
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@ -329,6 +329,7 @@ struct evp_cipher_st
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#define EVP_CIPH_CFB_MODE 0x3
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#define EVP_CIPH_OFB_MODE 0x4
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#define EVP_CIPH_CTR_MODE 0x5
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#define EVP_CIPH_GCM_MODE 0x6
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#define EVP_CIPH_MODE 0xF0007
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/* Set if variable length cipher */
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#define EVP_CIPH_VARIABLE_LENGTH 0x8
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@ -370,6 +371,9 @@ struct evp_cipher_st
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#define EVP_CTRL_RAND_KEY 0x6
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#define EVP_CTRL_PBE_PRF_NID 0x7
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#define EVP_CTRL_COPY 0x8
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#define EVP_CTRL_GCM_SET_IVLEN 0x9
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#define EVP_CTRL_GCM_GET_TAG 0x10
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#define EVP_CTRL_GCM_SET_TAG 0x11
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typedef struct evp_cipher_info_st
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{
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@ -770,6 +774,7 @@ const EVP_CIPHER *EVP_aes_128_cfb128(void);
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# define EVP_aes_128_cfb EVP_aes_128_cfb128
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const EVP_CIPHER *EVP_aes_128_ofb(void);
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const EVP_CIPHER *EVP_aes_128_ctr(void);
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const EVP_CIPHER *EVP_aes_128_gcm(void);
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const EVP_CIPHER *EVP_aes_192_ecb(void);
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const EVP_CIPHER *EVP_aes_192_cbc(void);
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const EVP_CIPHER *EVP_aes_192_cfb1(void);
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@ -778,6 +783,7 @@ const EVP_CIPHER *EVP_aes_192_cfb128(void);
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# define EVP_aes_192_cfb EVP_aes_192_cfb128
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const EVP_CIPHER *EVP_aes_192_ofb(void);
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const EVP_CIPHER *EVP_aes_192_ctr(void);
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const EVP_CIPHER *EVP_aes_192_gcm(void);
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const EVP_CIPHER *EVP_aes_256_ecb(void);
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const EVP_CIPHER *EVP_aes_256_cbc(void);
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const EVP_CIPHER *EVP_aes_256_cfb1(void);
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@ -786,6 +792,7 @@ const EVP_CIPHER *EVP_aes_256_cfb128(void);
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# define EVP_aes_256_cfb EVP_aes_256_cfb128
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const EVP_CIPHER *EVP_aes_256_ofb(void);
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const EVP_CIPHER *EVP_aes_256_ctr(void);
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const EVP_CIPHER *EVP_aes_256_gcm(void);
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#endif
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#ifndef OPENSSL_NO_CAMELLIA
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const EVP_CIPHER *EVP_camellia_128_ecb(void);
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