#ifndef OPENSSL_NO_ENGINE
#include <openssl/engine.h>
#endif
+#include "../constant_time_locl.h"
#include "evp_locl.h"
const char EVP_version[]="EVP" OPENSSL_VERSION_PTEXT;
ctx->cipher_data = NULL;
}
ctx->key_len = cipher->key_len;
- ctx->flags = 0;
+ /* Preserve wrap enable flag, zero everything else */
+ ctx->flags &= EVP_CIPHER_CTX_FLAG_WRAP_ALLOW;
if(ctx->cipher->flags & EVP_CIPH_CTRL_INIT)
{
if(!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_INIT, 0, NULL))
|| ctx->cipher->block_size == 8
|| ctx->cipher->block_size == 16);
+ if(!(ctx->flags & EVP_CIPHER_CTX_FLAG_WRAP_ALLOW)
+ && EVP_CIPHER_CTX_mode(ctx) == EVP_CIPH_WRAP_MODE)
+ {
+ EVPerr(EVP_F_EVP_CIPHERINIT_EX, EVP_R_WRAP_MODE_NOT_ALLOWED);
+ return 0;
+ }
+
if(!(EVP_CIPHER_CTX_flags(ctx) & EVP_CIPH_CUSTOM_IV)) {
switch(EVP_CIPHER_CTX_mode(ctx)) {
break;
}
}
+
if(key || (ctx->cipher->flags & EVP_CIPH_ALWAYS_CALL_INIT)) {
if(!ctx->cipher->init(ctx,key,iv,enc)) return 0;
int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
{
- int i,n;
- unsigned int b;
+ unsigned int i, b;
+ unsigned char pad, padding_good;
*outl=0;
if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER)
{
- i = ctx->cipher->do_cipher(ctx, out, NULL, 0);
- if (i < 0)
+ int ret = ctx->cipher->do_cipher(ctx, out, NULL, 0);
+ if (ret < 0)
return 0;
else
- *outl = i;
+ *outl = ret;
return 1;
}
- b=ctx->cipher->block_size;
+ b=(unsigned int)(ctx->cipher->block_size);
if (ctx->flags & EVP_CIPH_NO_PADDING)
{
if(ctx->buf_len)
return(0);
}
OPENSSL_assert(b <= sizeof ctx->final);
- n=ctx->final[b-1];
- if (n == 0 || n > (int)b)
- {
- EVPerr(EVP_F_EVP_DECRYPTFINAL_EX,EVP_R_BAD_DECRYPT);
- return(0);
- }
- for (i=0; i<n; i++)
+ pad=ctx->final[b-1];
+
+ padding_good = (unsigned char)(~constant_time_is_zero_8(pad));
+ padding_good &= constant_time_ge_8(b, pad);
+
+ for (i = 1; i < b; ++i)
{
- if (ctx->final[--b] != n)
- {
- EVPerr(EVP_F_EVP_DECRYPTFINAL_EX,EVP_R_BAD_DECRYPT);
- return(0);
- }
+ unsigned char is_pad_index = constant_time_lt_8(i, pad);
+ unsigned char pad_byte_good = constant_time_eq_8(ctx->final[b-i-1], pad);
+ padding_good &= constant_time_select_8(is_pad_index, pad_byte_good, 0xff);
}
- n=ctx->cipher->block_size-n;
- for (i=0; i<n; i++)
- out[i]=ctx->final[i];
- *outl=n;
+
+ /*
+ * At least 1 byte is always padding, so we always write b - 1
+ * bytes to avoid a timing leak. The caller is required to have |b|
+ * bytes space in |out| by the API contract.
+ */
+ for (i = 0; i < b - 1; ++i)
+ out[i] = ctx->final[i] & padding_good;
+ /* Safe cast: for a good padding, EVP_MAX_IV_LENGTH >= b >= pad */
+ *outl = padding_good & ((unsigned char)(b - pad));
+ return padding_good & 1;
}
else
- *outl=0;
- return(1);
+ {
+ *outl = 0;
+ return 1;
+ }
}
void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx)
return in->cipher->ctrl((EVP_CIPHER_CTX *)in, EVP_CTRL_COPY, 0, out);
return 1;
}
-