1use core::fmt;
 2
 3use super::{LOG_N, MODULUS, PK_LEN};
 4
 5#[derive(Clone, Debug, PartialEq, Eq)]
 6pub enum FalconError {
 7    KeyGenerationFailed,
 8    PubKeyDecodingExtraData,
 9    PubKeyDecodingInvalidCoefficient(u32),
10    PubKeyDecodingInvalidLength(usize),
11    PubKeyDecodingInvalidTag(u8),
12    SigDecodingTooBigHighBits(u32),
13    SigDecodingInvalidRemainder,
14    SigDecodingNonZeroUnusedBitsLastByte,
15    SigDecodingMinusZero,
16    SigDecodingIncorrectEncodingAlgorithm,
17    SigDecodingNotSupportedDegree(u8),
18    SigGenerationFailed,
19}
20
21impl fmt::Display for FalconError {
22    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
23        use FalconError::*;
24        match self {
25            KeyGenerationFailed => write!(f, "Failed to generate a private-public key pair"),
26            PubKeyDecodingExtraData => {
27                write!(f, "Failed to decode public key: input not fully consumed")
28            }
29            PubKeyDecodingInvalidCoefficient(val) => {
30                write!(f, "Failed to decode public key: coefficient {val} is greater than or equal to the field modulus {MODULUS}")
31            }
32            PubKeyDecodingInvalidLength(len) => {
33                write!(f, "Failed to decode public key: expected {PK_LEN} bytes but received {len}")
34            }
35            PubKeyDecodingInvalidTag(byte) => {
36                write!(f, "Failed to decode public key: expected the first byte to be {LOG_N} but was {byte}")
37            }
38            SigDecodingTooBigHighBits(m) => {
39                write!(f, "Failed to decode signature: high bits {m} exceed 2048")
40            }
41            SigDecodingInvalidRemainder => {
42                write!(f, "Failed to decode signature: incorrect remaining data")
43            }
44            SigDecodingNonZeroUnusedBitsLastByte => {
45                write!(f, "Failed to decode signature: Non-zero unused bits in the last byte")
46            }
47            SigDecodingMinusZero => write!(f, "Failed to decode signature: -0 is forbidden"),
48            SigDecodingIncorrectEncodingAlgorithm => write!(f, "Failed to decode signature: not supported encoding algorithm"),
49            SigDecodingNotSupportedDegree(log_n) => write!(f, "Failed to decode signature: only supported irreducible polynomial degree is 512, 2^{log_n} was provided"),
50            SigGenerationFailed => write!(f, "Failed to generate a signature"),
51        }
52    }
53}
54
55#[cfg(feature = "std")]
56impl std::error::Error for FalconError {}