Add unmaintained crate informational advisory: rust-crypto

No releases since May 2016, no commits since September 2016, with
62 open issues and 37 open PRs.

Author is unresponsive:

DaGenix/rust-crypto#440

Advisory includes a large list of maintained "successor" crates:
`rust-crypto` was a kitchen sink of functionality, so the advisory
contains a list of potential successor crates each with an
algorithm-by-algorithm breakdown of what they support.

crates/rust-crypto/RUSTSEC-0000-0000.toml

@@ -0,0 +1,78 @@
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "rust-crypto"
+title = "rust-crypto is unmaintained; switch to a modern alternative"
+informational = "unmaintained"
+date = "2018-09-06" # last GitHub commit
+url = "https://github.com/DaGenix/rust-crypto/issues/440"
+unaffected_versions = ["> 0.2.36"] # last release
+description = """
+The `rust-crypto` crate has not seen a release or GitHub commit since 2016,
+and its author is unresponsive.
+
+We recommend you switch to one of the following crates instead, depending on
+which algorithms you need:
+
+- [dalek-cryptography GitHub Org]:
+  - Key agreement: [`x25519-dalek`]
+  - Signature algorithms: [`ed25519-dalek`]
+- [`ring`]:
+  - AEAD algorithms: AES-GCM, ChaCha20Poly1305
+  - Digest algorithms: SHA-256, SHA-384, SHA-512, SHA-512/256 (legacy: SHA-1)
+  - HMAC
+  - Key agreement: ECDH (P-256, P-384), X25519
+  - Key derivation: HKDF
+  - Password hashing: PBKDF2
+  - Signature algorithms: ECDSA (P-256, P-384), Ed25519, RSA (PKCS#1v1.5, PSS)
+- [RustCrypto GitHub Org]:
+  - AEAD algorithms: [`aes-gcm`], [`aes-gcm-siv`], [`aes-siv`], [`chacha20poly1305`], [`xsalsa20poly1305`]
+  - Block ciphers: [`aes`], [`cast5`], [`des`]
+  - Digest algorithms: [`sha2`], [`sha3`], [`blake2`], [`ripemd160`] (legacy: [`sha-1`])
+  - Key derivation: [`hkdf`]
+  - MACs: [`cmac`], [`hmac`], [`pmac`], [`poly1305`]
+  - Password hashing: [`pbkdf2`]
+  - Stream ciphers: [`aes-ctr`], [`chacha20`], [`hc-256`], [`salsa20`]
+- [`secp256k1`]:
+  - Key agreement: ECDH (secp256k1 only)
+  - Signature algorithms: ECDSA (secp256k1 only)
+- [`sodiumoxide`]:
+  - AEAD algorithms: ChaCha20Poly1305 (IETF version)
+  - Digest algorithms: SHA-256, SHA-512
+  - HMAC
+  - Key agreement: X25519 + BLAKE2b
+  - Password hashing: Argon2(i/d), scrypt
+  - Public key encryption: NaCl "Box" (X25519 + XSalsa20Poly1305)
+  - Signature algorithms: Ed25519
+  - Short-input PRF: SipHash24
+
+[dalek-cryptography GitHub Org]: https://github.com/dalek-cryptography
+[RustCrypto GitHub Org]: https://github.com/RustCrypto
+[`aes`]: https://crates.io/crates/aes
+[`aes-ctr`]: https://crates.io/crates/aes-ctr
+[`aes-gcm`]: https://crates.io/crates/aes-gcm
+[`aes-gcm-siv`]: https://crates.io/crates/aes-gcm-siv
+[`aes-siv`]: https://crates.io/crates/aes-siv
+[`blake2`]: https://crates.io/crates/blake2
+[`cast5`]: https://crates.io/crates/cast5
+[`chacha20`]: https://crates.io/crates/chacha20
+[`chacha20poly1305`]: https://crates.io/crates/chacha20poly1305
+[`cmac`]: https://crates.io/crates/cmac
+[`des`]: https://crates.io/crates/des
+[`ed25519-dalek`]: https://crates.io/crates/ed25519-dalek
+[`hc-256`]: https://crates.io/crates/hc-256
+[`hkdf`]: https://crates.io/crates/hkdf
+[`hmac`]: https://crates.io/crates/hmac
+[`pbkdf2`]: https://crates.io/crates/pbkdf2
+[`pmac`]: https://crates.io/crates/pmac
+[`poly1305`]: https://crates.io/crates/poly1305
+[`ring`]: https://crates.io/crates/ring
+[`ripemd160`]: https://crates.io/crates/ripemd160
+[`salsa20`]: https://crates.io/crates/salsa20
+[`secp256k1`]: https://crates.io/crates/secp256k1
+[`sha-1`]: https://crates.io/crates/sha-1
+[`sha2`]: https://crates.io/crates/sha2
+[`sha3`]: https://crates.io/crates/sha3
+[`sodiumoxide`]: https://crates.io/crates/sodiumoxide
+[`x25519-dalek`]: https://crates.io/crates/x25519-dalek
+[`xsalsa20poly1305`]: https://crates.io/crates/xsalsa20poly1305
+"""