116 lines
4.1 KiB
Rust
116 lines
4.1 KiB
Rust
use num_bigint::BigUint;
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use crate::common_types::{DnsSecAlgorithm, DnsSecAlgorithmKnown};
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// ECC_GOST [RFC5933]
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// RFC5702 still confirms this
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const RSA_BITS_LIMIT: usize = 4096;
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const RSA_BYTES_LIMIT: usize = RSA_BITS_LIMIT / 8;
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fn parse_rsa(data: &[u8]) -> crate::errors::Result<PublicKey> {
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failure::ensure!(!data.is_empty(), "RSA public key must be non-empty");
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let exp_len: usize;
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let offset: usize;
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if data[0] == 0 {
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failure::ensure!(data.len() >= 3, "RSA public key: unexpected end of data when decoding exponent length");
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exp_len = (data[1] as usize) << 8 + (data[2] as usize);
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offset = 3;
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failure::ensure!(exp_len >= 256, "RSA public key: exponent length in long form but too small");
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} else {
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exp_len = data[0] as usize;
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offset = 1;
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}
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assert!(exp_len > 0); // should be unreachable: 0 means two bytes, which are checked for >= 256
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failure::ensure!(exp_len <= RSA_BYTES_LIMIT, "RSA public key: exponent too long (limit: {} bits)", RSA_BITS_LIMIT);
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failure::ensure!(data.len() >= offset + exp_len, "RSA public key: unexpected end of data when reading exponent");
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failure::ensure!(data[offset] != 0, "RSA public key: leading zero in exponent");
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let exponent = BigUint::from_bytes_be(&data[offset..][..exp_len]);
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let modulus_data = &data[offset..][exp_len..];
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failure::ensure!(modulus_data.len() <= RSA_BYTES_LIMIT, "RSA public key: modulus too long (limit: {} bits)", RSA_BITS_LIMIT);
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failure::ensure!(!modulus_data.is_empty(), "RSA public key: modulus empty");
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failure::ensure!(modulus_data[offset] != 0, "RSA public key: leading zero in modulus");
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let modulus = BigUint::from_bytes_be(modulus_data);
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Ok(PublicKey::RSA {
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exponent,
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modulus,
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})
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}
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#[allow(non_camel_case_types)]
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pub enum PublicKey {
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RSA { exponent: BigUint, modulus: BigUint },
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ECDSAP256 { xy: Box<([u8; 32], [u8; 32])> },
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ECDSAP384 { xy: Box<([u8; 48], [u8; 48])> },
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ECC_GOST { xy: Box<([u8; 32], [u8; 32])> },
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ED25519 { key: Box<[u8; 32]> },
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ED448 { key: Box<[u8; 57]> },
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}
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impl PublicKey {
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pub fn parse(algorithm: DnsSecAlgorithm, data: &[u8]) -> crate::errors::Result<Self> {
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use DnsSecAlgorithmKnown::*;
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let algorithm = algorithm.into_known().ok_or_else(|| failure::format_err!("Unknown algorithm"))?;
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match algorithm {
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DELETE|INDIRECT|PRIVATEDNS|PRIVATEOID => failure::bail!("Algorithm {:?} not used with actual key", algorithm),
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RSAMD5|RSASHA1|RSASHA1_NSEC3_SHA1|RSASHA256|RSASHA512 => parse_rsa(data),
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DH|DSA|DSA_NSEC3_SHA1 => failure::bail!("Algorithm {:?} not supported", algorithm),
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ECDSAP256SHA256 => {
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failure::ensure!(data.len() == 64, "Expected 64 bytes public key for ECDSAP256");
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let mut x = [0u8; 32];
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x.copy_from_slice(&data[..32]);
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let mut y = [0u8; 32];
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y.copy_from_slice(&data[32..]);
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Ok(PublicKey::ECDSAP256 { xy: Box::new((x, y)) })
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},
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ECDSAP384SHA384 => {
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failure::ensure!(data.len() == 96, "Expected 96 bytes public key for ECDSAP384");
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let mut x = [0u8; 48];
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x.copy_from_slice(&data[..48]);
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let mut y = [0u8; 48];
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y.copy_from_slice(&data[48..]);
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Ok(PublicKey::ECDSAP384 { xy: Box::new((x, y)) })
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},
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ECC_GOST => {
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failure::ensure!(data.len() == 64, "Expected 64 bytes public key for ECC_GOST");
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let mut x = [0u8; 32];
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x.copy_from_slice(&data[..32]);
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let mut y = [0u8; 32];
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y.copy_from_slice(&data[32..]);
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Ok(PublicKey::ECC_GOST { xy: Box::new((x, y)) })
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},
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ED25519 => {
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failure::ensure!(data.len() == 32, "Expected 32 bytes public key for ED25519");
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let mut key = [0u8; 32];
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key.copy_from_slice(data);
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Ok(PublicKey::ED25519 { key: Box::new(key) })
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},
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ED448 => {
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failure::ensure!(data.len() == 57, "Expected 57 bytes public key for ED448");
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let mut key = [0u8; 57];
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key.copy_from_slice(data);
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Ok(PublicKey::ED448 { key: Box::new(key) })
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},
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}
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}
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pub fn bits(&self) -> Option<u32> {
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match self {
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PublicKey::RSA { modulus, .. } => Some(modulus.bits() as u32),
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PublicKey::ECDSAP256 { .. } => Some(32*8),
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PublicKey::ECDSAP384 { .. } => Some(48*8),
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PublicKey::ECC_GOST { .. } => Some(32*8),
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PublicKey::ED25519 { .. } => Some(32*8),
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PublicKey::ED448 { .. } => Some(57*8),
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}
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}
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}
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