Create certificates

Recipe	Crates	Categories
DER
pem-rfc7468
pkcs8
x509-cert

Cryptographic certificates, also known as digital certificates, are electronic credentials used to establish the identity of entities such as individuals, websites, or organizations in online communications. They are issued by trusted entities called Certificate Authorities (CAs) and contain a public key, the owner's identity, and the CA's digital signature. When a certificate is presented, it allows the recipient to verify the identity of the sender and securely exchange information using the public key. These certificates are fundamental to protocols like SSL/TLS, which ensure secure communication over the internet.

For more formats, see Rust Crypto Formats.

• der
• pem-rfc7468
• pkcs8
• x509-cert

DER

der⮳ is a pure Rust embedded-friendly implementation of the Distinguished Encoding Rules (DER) for Abstract Syntax Notation One (ASN.1) as described in ITU X.690 with full support for heapless no_std targets. DER (Distinguished Encoding Rules) certificates are a binary format for X.509 digital certificates, commonly used for representing cryptographic keys and identities. X.509 certificates bind a public key to an identity (e.g., a name, an email address, or a domain name). This binding is validated by a trusted third party, known as a Certificate Authority (CA).

use der::Decode;
use der::Encode;
use der::Sequence;

// This example demonstrates how to encode a struct to DER format, and decode it
// back using the `der` crate.

// Define a struct to be encoded/decoded
// Note that we derive the `Sequence` trait.
#[derive(Debug, PartialEq, Sequence)]
struct MyStruct {
    field1: u32,
    field2: String,
}
fn main() {
    // Create an instance of MyStruct
    let my_struct = MyStruct {
        field1: 42,
        field2: "Hello, DER!".to_string(),
    };

    // Encode the struct to DER
    let der_encoded = my_struct.to_der().expect("Failed to encode");
    println!("DER Encoded: {:?}", der_encoded);

    // Decode the DER back to MyStruct
    let decoded_struct =
        MyStruct::from_der(&der_encoded).expect("Failed to decode");
    println!("Decoded Struct: {:?}", decoded_struct);

    // Verify that the decoded struct matches the original
    assert_eq!(my_struct, decoded_struct);
}

pem-rfc7468

PEM (Privacy Enhanced Mail) is a text-based format (Base64 encoded DER) commonly used for cryptographic keys, certificates, and other data structures.

pem-rfc7468⮳ implements PEM Encoding (RFC 7468) for PKIX, PKCS, and CMS Structures, implementing a strict subset of the original Privacy-Enhanced Mail encoding intended specifically for use with cryptographic keys, certificates, and other messages. It provides a no_std-friendly, constant-time implementation suitable for use with cryptographic private keys.

// use pem_rfc7468::LineEnding;
// use pem_rfc7468::decode_vec;
// use pem_rfc7468::encode_string;

// fn main() -> Result<(), Box<dyn std::error::Error>> {
//     // Example DER-encoded data (replace with your actual data)
//     let der_data = vec![
//         0x30, 0x82, 0x01, 0x22, 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48,
// 0x86,         0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00, 0x04, 0x20, 0x41,
// 0x20, 0x42,         0x20, 0x43, 0x20, 0x20, 0x48,
//     ];

//     // Encode DER data to PEM
//     let type_label = "MY_DATA";
//     let pem_encoded =
//         encode_string(type_label, LineEnding::default(), &der_data)?;
//     // Specifies the line ending for PEM encoding (default is \r\n).

//     println!("PEM-encoded data:\n{}", pem_encoded);

//     // Decode PEM data back to DER
//     let (decoded_type_label, decoded_data) =
//         decode_vec(pem_encoded.as_bytes())?;

//     assert_eq!(type_label, decoded_type_label);
//     assert_eq!(der_data, decoded_data);

//     println!("Successfully decoded PEM data.");

//     Ok(())
// }

pkcs8

PKCS#8 ("Public-Key Cryptography Standards (PKCS) #8": Private-Key Information Syntax Specification - RFC 5208) is a standard syntax for storing private key information, including both private keys and optional attributes, in a secure format. pkcs8⮳ is a pure Rust implementation thereof, with additional support for PKCS#8v2 asymmetric key packages (RFC 5958).

use std::fs::File;
use std::io::Write;

use base64ct::LineEnding;
// Trait to parse a private key from a PKCS#8 encoded document.
use pkcs8::DecodePrivateKey;
// Trait to serialize a private key to a PKCS#8 encoded document.
use pkcs8::EncodePrivateKey;
// Operating System's Random Number Generator
use rand::rngs::OsRng;
use rsa::RsaPrivateKey;
// Components of an RSA private key
use rsa::traits::PrivateKeyParts;

// Encoding and decoding private keys in PKCS#8 format.
// PKCS #8 is a standard syntax for storing private key information.
// PKCS #8 private keys are typically exchanged in the PEM base64-encoded file
// format PEM is a method of encoding binary data as a string (also known as
// ASCII armor). It contains a header and a footer line (specifying the type of
// data that is encoded and showing begin/end if the data is chained together)
// and the data in the middle is the base 64 data.
fn main() -> anyhow::Result<()> {
    // Generate an RSA keypair
    let mut rng = OsRng;
    let private_key = RsaPrivateKey::new(&mut rng, 2048)?;

    // Encode the private key in PKCS#8 format
    let pkcs8_pem = private_key.to_pkcs8_pem(LineEnding::LF)?;

    // Save the PKCS#8 key to a file
    let mut file = File::create("private_key.pem")?;
    file.write_all(pkcs8_pem.as_bytes())?;
    file.flush()?;

    // Read the PKCS#8 key from the file
    let pem: String = std::fs::read_to_string("private_key.pem")?;

    // Decode the private key from PKCS#8
    let decoded_private_key = RsaPrivateKey::from_pkcs8_pem(&pem)?;

    // Verify that the decoded key is the same as the original
    assert_eq!(private_key.primes(), decoded_private_key.primes());

    println!("Successfully read and decoded PKCS#8 private key.");

    Ok(())
}

x509-cert

An X.509 certificate is a standardized format for public key certificates used in various internet protocols, including SSL/TLS, to secure communications over networks. These certificates contain information about the certificate holder (such as a website or individual), their public key, the issuing Certificate Authority (CA), and a digital signature from the CA. They help verify the identity of entities and establish encrypted connections, ensuring the confidentiality and integrity of the data being exchanged. x509-cert⮳ is a pure Rust implementation of the X.509 Public Key Infrastructure Certificate format as described in RFC 5280.

// use std::fs::File;
// use std::io::BufReader;

// use chrono::Utc;
// use rustls::internal::pemfile::certs;
// use rustls::internal::pemfile::rsa_private_keys;
// use x509_cert::builder::CertificateBuilder;
// use x509_cert::builder::Profile;
// use x509_cert::name::Name;
// use x509_cert::serial_number::SerialNumber;
// use x509_cert::time::Duration;
// use x509_cert::time::Time;

// fn main() -> anyhow::Result<()> {
//     // Load existing certificate and private key (replace with your actual
//     // paths)
//     let cert_file = File::open("path/to/your/cert.pem")?;
//     let key_file = File::open("path/to/your/key.pem")?;
//     let cert_reader = BufReader::new(cert_file);
//     let key_reader = BufReader::new(key_file);

//     let certs = certs(&mut cert_reader).unwrap();
//     let keys = rsa_private_keys(&mut key_reader).unwrap();

//     // Create a new certificate builder
//     let now = Utc::now();
//     let not_before = Time::from(now);
//     let not_after = Time::from(now + Duration::days(365)); // Valid for one
// year     let serial_number = SerialNumber::random();
//     let subject = Name::build_common_name("example.com").unwrap();
//     let issuer = subject.clone();

//     let mut builder = CertificateBuilder::new(
//         Profile::Server,
//         serial_number,
//         Validity {
//             not_before,
//             not_after,
//         },
//         issuer,
//         subject,
//     )?;

//     // Add extensions (optional)
//     // ...

//     // Sign the certificate
//     let certificate = builder.sign(&keys[0])?;

//     // Print or save the certificate (DER encoding)
//     println!("Certificate: {:?}", certificate.to_der()?);

//     Ok(())
// }