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libtomcrypt/libtomcrypt-two-key-triple-...

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From 445dfa67a64dcd30067dab823f6bae31d1019c1e Mon Sep 17 00:00:00 2001
From: Paul Howarth <paul@city-fan.org>
Date: Tue, 15 Apr 2014 11:25:18 +0100
Subject: [PATCH] des.c: Add support for two-key Triple-DES
Add two-key 3DES support, needed by pycrypto.
This commit is based on the one for the bundled libtomcrypt 1.16
code in pycrypto:
https://github.com/dlitz/pycrypto/commit/65085f16
---
src/ciphers/des.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/src/ciphers/des.c b/src/ciphers/des.c
index af3a4d0..0034c80 100644
--- a/src/ciphers/des.c
+++ b/src/ciphers/des.c
@@ -1562,17 +1562,27 @@ int des3_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_k
return CRYPT_INVALID_ROUNDS;
}
- if (keylen != 24) {
+ if (keylen != 24 && keylen != 16) {
return CRYPT_INVALID_KEYSIZE;
}
deskey(key, EN0, skey->des3.ek[0]);
deskey(key+8, DE1, skey->des3.ek[1]);
- deskey(key+16, EN0, skey->des3.ek[2]);
+ if (keylen == 24) {
+ deskey(key+16, EN0, skey->des3.ek[2]);
+ } else {
+ /* two-key 3DES: K3=K1 */
+ deskey(key, EN0, skey->des3.ek[2]);
+ }
deskey(key, DE1, skey->des3.dk[2]);
deskey(key+8, EN0, skey->des3.dk[1]);
- deskey(key+16, DE1, skey->des3.dk[0]);
+ if (keylen == 24) {
+ deskey(key+16, DE1, skey->des3.dk[0]);
+ } else {
+ /* two-key 3DES: K3=K1 */
+ deskey(key, DE1, skey->des3.dk[0]);
+ }
return CRYPT_OK;
}
--
1.9.0