[WIP] ssh-encoding: PEM line width detection

Uses the line width detection support added to `pem-rfc7468` in
RustCrypto/formats#1464 to automatically detect the input line width and
parse PEM documents accordingly, which allows support for a wider range
of SSH keys which don't use the default 70 chars of line wrapping.

Closes #195

Cargo.toml

@@ -14,3 +14,4 @@ opt-level = 2
 [patch.crates-io]
 # https://github.com/dalek-cryptography/curve25519-dalek/pull/676
 ed25519-dalek = { git = "https://github.com/dalek-cryptography/curve25519-dalek.git", branch = "rustcrypto-new-releases" }
+pem-rfc7468 = { git = "https://github.com/RustCrypto/formats", branch = "pem-rfc7468/v1.0.0-rc.1" }

ssh-encoding/Cargo.toml

@@ -18,7 +18,7 @@ rust-version = "1.60"
 [dependencies]
 base64ct = { version = "1.4", optional = true }
 bytes = { version = "1", optional = true, default-features = false }
-pem-rfc7468 = { version = "1.0.0-rc.0", optional = true }
+pem-rfc7468 = { version = "1.0.0-rc.1", optional = true }
 sha2 = { version = "=0.11.0-pre.4", optional = true, default-features = false }
 
 [dev-dependencies]

ssh-encoding/src/pem/reader.rs

@@ -1,4 +1,3 @@
-use super::LINE_WIDTH;
 use crate::{Decode, Error, Reader, Result};
 
 /// Inner PEM decoder.
@@ -14,11 +13,9 @@ pub struct PemReader<'i> {
 }
 
 impl<'i> PemReader<'i> {
-    /// Create a new PEM reader.
-    ///
-    /// Uses [`LINE_WIDTH`] as the default line width (i.e. 70 chars).
+    /// Create a new PEM reader which autodetects the line width of the input.
     pub fn new(pem: &'i [u8]) -> Result<Self> {
-        let inner = Inner::new_wrapped(pem, LINE_WIDTH)?;
+        let inner = Inner::new_detect_wrap(pem)?;
         let remaining_len = inner.remaining_len();
 
         Ok(Self {

ssh-key/tests/examples/id_ed25519.64cols

@@ -0,0 +1,8 @@
+-----BEGIN OPENSSH PRIVATE KEY-----
+b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAMwAAAAtz
+c2gtZWQyNTUxOQAAACCzPq7zfqLffKoBDe/eo04kH2XxtSmk9D7RQyf1xUqrYgAA
+AJgAIAxdACAMXQAAAAtzc2gtZWQyNTUxOQAAACCzPq7zfqLffKoBDe/eo04kH2Xx
+tSmk9D7RQyf1xUqrYgAAAEC2BsIi0QwW2uFscKTUUXNHLsYX4FxlaSDSblbAj7WR
+7bM+rvN+ot98qgEN796jTiQfZfG1KaT0PtFDJ/XFSqtiAAAAEHVzZXJAZXhhbXBs
+ZS5jb20BAgMEBQ==
+-----END OPENSSH PRIVATE KEY-----

ssh-key/tests/private_key.rs

@@ -34,6 +34,9 @@ const OPENSSH_ECDSA_P521_EXAMPLE: &str = include_str!("examples/id_ecdsa_p521");
 /// Ed25519 OpenSSH-formatted private key
 const OPENSSH_ED25519_EXAMPLE: &str = include_str!("examples/id_ed25519");
 
+/// Ed25519 OpenSSH-formatted private key with 64-column line wrapping
+const OPENSSH_ED25519_64COLS_EXAMPLE: &str = include_str!("examples/id_ed25519.64cols");
+
 /// RSA (3072-bit) OpenSSH-formatted public key
 #[cfg(feature = "alloc")]
 const OPENSSH_RSA_3072_EXAMPLE: &str = include_str!("examples/id_rsa_3072");
@@ -247,6 +250,14 @@ fn decode_ed25519_openssh() {
     assert_eq!(key.comment(), "user@example.com");
 }
 
+/// Test alternative PEM line wrappings (64 columns).
+#[test]
+fn decode_ed25519_openssh_64cols() {
+    let key = PrivateKey::from_openssh(OPENSSH_ED25519_64COLS_EXAMPLE).unwrap();
+    let other_key = PrivateKey::from_openssh(OPENSSH_ED25519_EXAMPLE).unwrap();
+    assert_eq!(key, other_key);
+}
+
 #[cfg(feature = "alloc")]
 #[test]
 fn decode_rsa_3072_openssh() {