Use a unified error set for std/crypto/*

This ensures that errors are used consistently across all operations.

lib/std/crypto/error.zig

@@ -0,0 +1,34 @@
+pub const Error = error{
+    /// MAC verification failed - The tag doesn't verify for the given ciphertext and secret key
+    AuthenticationFailed,
+
+    /// The requested output length is too long for the chosen algorithm
+    OutputTooLong,
+
+    /// Finite field operation returned the identity element
+    IdentityElement,
+
+    /// Encoded input cannot be decoded
+    InvalidEncoding,
+
+    /// The signature does't verify for the given message and public key
+    SignatureVerificationFailed,
+
+    /// Both a public and secret key have been provided, but they are incompatible
+    KeyMismatch,
+
+    /// Encoded input is not in canonical form
+    NonCanonical,
+
+    /// Square root has no solutions
+    NotSquare,
+
+    /// Verification string doesn't match the provided password and parameters
+    PasswordVerificationFailed,
+
+    /// Parameters would be insecure to use
+    WeakParameters,
+
+    /// Public key would be insecure to use
+    WeakPublicKey,
+};