srp: rebuild library (#79)

Complete rewrite of the SRP library.

Includes many improvements over the old library:

- Improved file and code organization
- Access to individual SRP computations 
- Consistent sever and client API
- Simpler API
- Improved documentation with tests in documentation
- New tests for compatibility with the RFC
- Bumps dependencies
- Timing safe verification comparisons
- Modernized error handling 

1 files changed, 135 insertions, 0 deletions

diff --git a/srp/tests/rfc5054.rs b/srp/tests/rfc5054.rs
new file mode 100644
index 0000000..e1aa711
--- /dev/null
+++ b/srp/tests/rfc5054.rs
@@ -0,0 +1,135 @@
+use hex_literal::hex;
+use num_bigint::BigUint;
+use sha1::Sha1;
+use srp::client::SrpClient;
+use srp::groups::G_1024;
+use srp::server::SrpServer;
+use srp::utils::{compute_k, compute_u};
+
+#[test]
+#[allow(clippy::many_single_char_names)]
+fn rfc5054() {
+    let i = b"alice";
+    let p = b"password123";
+    let s = hex!("BEB25379 D1A8581E B5A72767 3A2441EE");
+    let group = &G_1024;
+
+    let k = compute_k::<Sha1>(group);
+
+    assert_eq!(
+        k.to_bytes_be(),
+        hex!("7556AA04 5AEF2CDD 07ABAF0F 665C3E81 8913186F"),
+        "bad k value"
+    );
+
+    let identity_hash = SrpClient::<Sha1>::compute_identity_hash(i, p);
+    let x = SrpClient::<Sha1>::compute_x(identity_hash.as_slice(), &s);
+
+    assert_eq!(
+        x.to_bytes_be(),
+        hex!("94B7555A ABE9127C C58CCF49 93DB6CF8 4D16C124"),
+        "bad x value"
+    );
+
+    let client = SrpClient::<Sha1>::new(group);
+    let v = client.compute_v(&x);
+
+    assert_eq!(
+        v.to_bytes_be(),
+        hex!(
+            "        
+         7E273DE8 696FFC4F 4E337D05 B4B375BE B0DDE156 9E8FA00A 9886D812
+         9BADA1F1 822223CA 1A605B53 0E379BA4 729FDC59 F105B478 7E5186F5
+         C671085A 1447B52A 48CF1970 B4FB6F84 00BBF4CE BFBB1681 52E08AB5
+         EA53D15C 1AFF87B2 B9DA6E04 E058AD51 CC72BFC9 033B564E 26480D78
+         E955A5E2 9E7AB245 DB2BE315 E2099AFB
+         "
+        ),
+        "bad v value"
+    );
+
+    let a = BigUint::from_bytes_be(&hex!(
+        "
+    60975527 035CF2AD 1989806F 0407210B C81EDC04 E2762A56 AFD529DD
+    DA2D4393"
+    ));
+
+    let b = BigUint::from_bytes_be(&hex!(
+        "
+    E487CB59 D31AC550 471E81F0 0F6928E0 1DDA08E9 74A004F4 9E61F5D1
+    05284D20"
+    ));
+
+    let a_pub = client.compute_a_pub(&a);
+
+    assert_eq!(
+        a_pub.to_bytes_be(),
+        hex!(
+            "
+         61D5E490 F6F1B795 47B0704C 436F523D D0E560F0 C64115BB 72557EC4
+         4352E890 3211C046 92272D8B 2D1A5358 A2CF1B6E 0BFCF99F 921530EC
+         8E393561 79EAE45E 42BA92AE ACED8251 71E1E8B9 AF6D9C03 E1327F44
+         BE087EF0 6530E69F 66615261 EEF54073 CA11CF58 58F0EDFD FE15EFEA
+         B349EF5D 76988A36 72FAC47B 0769447B
+         "
+        ),
+        "bad a_pub value"
+    );
+
+    let server = SrpServer::<Sha1>::new(group);
+    let b_pub = server.compute_b_pub(&b, &k, &v);
+
+    assert_eq!(
+        b_pub.to_bytes_be(),
+        hex!(
+            "
+         BD0C6151 2C692C0C B6D041FA 01BB152D 4916A1E7 7AF46AE1 05393011
+         BAF38964 DC46A067 0DD125B9 5A981652 236F99D9 B681CBF8 7837EC99
+         6C6DA044 53728610 D0C6DDB5 8B318885 D7D82C7F 8DEB75CE 7BD4FBAA
+         37089E6F 9C6059F3 88838E7A 00030B33 1EB76840 910440B1 B27AAEAE
+         EB4012B7 D7665238 A8E3FB00 4B117B58
+         "
+        ),
+        "bad b_pub value"
+    );
+
+    let u = compute_u::<Sha1>(&a_pub.to_bytes_be(), &b_pub.to_bytes_be());
+
+    assert_eq!(
+        u.to_bytes_be(),
+        hex!("CE38B959 3487DA98 554ED47D 70A7AE5F 462EF019"),
+        "bad u value"
+    );
+
+    assert_eq!(
+        client
+            .compute_premaster_secret(&b_pub, &k, &x, &a, &u)
+            .to_bytes_be(),
+        hex!(
+            "
+         B0DC82BA BCF30674 AE450C02 87745E79 90A3381F 63B387AA F271A10D
+         233861E3 59B48220 F7C4693C 9AE12B0A 6F67809F 0876E2D0 13800D6C
+         41BB59B6 D5979B5C 00A172B4 A2A5903A 0BDCAF8A 709585EB 2AFAFA8F
+         3499B200 210DCC1F 10EB3394 3CD67FC8 8A2F39A4 BE5BEC4E C0A3212D
+         C346D7E4 74B29EDE 8A469FFE CA686E5A
+         "
+        ),
+        "bad client premaster"
+    );
+
+    assert_eq!(
+        server
+            .compute_premaster_secret(&a_pub, &v, &u, &b)
+            .to_bytes_be(),
+        hex!(
+            "
+         B0DC82BA BCF30674 AE450C02 87745E79 90A3381F 63B387AA F271A10D
+         233861E3 59B48220 F7C4693C 9AE12B0A 6F67809F 0876E2D0 13800D6C
+         41BB59B6 D5979B5C 00A172B4 A2A5903A 0BDCAF8A 709585EB 2AFAFA8F
+         3499B200 210DCC1F 10EB3394 3CD67FC8 8A2F39A4 BE5BEC4E C0A3212D
+         C346D7E4 74B29EDE 8A469FFE CA686E5A
+         "
+        ),
+        "bad server premaster"
+    );
+}