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-rw-r--r--lib/crypto/aes.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/lib/crypto/aes.c b/lib/crypto/aes.c
index 7735e8ff37..a47a456593 100644
--- a/lib/crypto/aes.c
+++ b/lib/crypto/aes.c
@@ -112,3 +112,25 @@ AES_cbc_encrypt(const unsigned char *in, unsigned char *out,
}
}
}
+
+void aes_cfb8_encrypt(const uint8_t *in, uint8_t *out,
+ size_t length, const AES_KEY *key,
+ uint8_t *iv, int forward)
+{
+ size_t i;
+
+ for (i=0; i < length; i++) {
+ uint8_t tiv[AES_BLOCK_SIZE*2];
+
+ memcpy(tiv, iv, AES_BLOCK_SIZE);
+ AES_encrypt(iv, iv, key);
+ if (!forward) {
+ tiv[AES_BLOCK_SIZE] = in[i];
+ }
+ out[i] = in[i] ^ iv[0];
+ if (forward) {
+ tiv[AES_BLOCK_SIZE] = out[i];
+ }
+ memcpy(iv, tiv+1, AES_BLOCK_SIZE);
+ }
+}