synta-tools

Table of Contents generated with DocToc

• Installation
• Commands
  • cert
  • asn1parse
• Future Commands
• Development

Command-line tools for inspecting and manipulating ASN.1 DER and PEM files.

Installation

cargo install --path .

Or run directly from the workspace:

cargo run -p synta-tools -- <command> [options]

Commands

cert

Inspect X.509 certificates and display human-readable information (similar to openssl x509 -noout -text).

Usage:

synta-tool cert <file> [options]

Options:

• -v, --verbose - Show detailed information including extensions and signature value
• -f, --format <FORMAT> - Output format: text (default) or json

Examples:

Inspect a certificate:

synta-tool cert certificate.pem

Show detailed information:

synta-tool cert certificate.pem --verbose

Output as JSON:

synta-tool cert certificate.pem --format json

Sample Output (text format):

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 1 (0x1)
        Signature Algorithm: sha256WithRSAEncryption
        Issuer: CN=Test CA
        Validity
            Not Before: Jan  1 00:00:00 2023 GMT
            Not After : Jan  1 00:00:00 2024 GMT
        Subject: CN=Test CA
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:ab:58:...
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Basic Constraints: critical
                CA:TRUE
            X509v3 Subject Key Identifier:
                0A:1C:69:EF:...
            X509v3 Authority Key Identifier:
                keyid:0A:1C:69:EF:...
    Signature Algorithm: sha256WithRSAEncryption
    Signature Value:
        66:f3:75:...

Sample Output (JSON format):

{
  "version": 3,
  "serial_number": "01",
  "signature_algorithm": "sha256WithRSAEncryption",
  "issuer": "CN=Test CA",
  "not_before": "Jan  1 00:00:00 2023 GMT",
  "not_after": "Jan  1 00:00:00 2024 GMT",
  "subject": "CN=Test CA",
  "public_key_algorithm": "rsaEncryption",
  "public_key_bits": 2048
}

asn1parse

Parse and display ASN.1 structure similar to openssl asn1parse.

Usage:

synta-tool asn1parse [file] [options]

Omitting file or passing - reads from standard input.

Options:

• -o, --offset <OFFSET> - Start parsing at byte offset (default: 0)
• -m, --mode <MODE> - Output mode: text (default), openssl, or hex
• -I, --inform <INFORM> - Input format: auto (default), pem, der, or hex

Examples:

Parse a PEM or DER file (format auto-detected):

synta-tool asn1parse certificate.pem
synta-tool asn1parse certificate.der

Parse starting at a specific byte offset:

synta-tool asn1parse data.der --offset 4

Parse hex-encoded bytes from stdin (continuous, space-, or colon-separated):

echo "3006020101020102" | synta-tool asn1parse --inform hex
echo "30 06 02 01 01 02 01 02" | synta-tool asn1parse --inform hex
echo "30:06:02:01:01:02:01:02" | synta-tool asn1parse --inform hex

Parse a hexdump with address offsets (hexdump, Wireshark, or xxd output):

# hexdump / Wireshark style (offset + 2+ spaces)
synta-tool asn1parse capture.txt --inform hex

# xxd style (colon after offset, space-separated pairs or 4-char groups)
xxd -g 1 data.bin | synta-tool asn1parse --inform hex
xxd data.bin | synta-tool asn1parse --inform hex

Round-trip: dump raw bytes as hex then re-parse:

synta-tool asn1parse certificate.pem --mode hex | synta-tool asn1parse --inform hex

OpenSSL-compatible output with byte offsets:

synta-tool asn1parse certificate.pem --mode openssl

Output Format:

The default text mode renders an indented tree. String types (UTF8String, PrintableString, IA5String, etc.) and OCTET STRING values that contain printable UTF-8 text show the decoded string followed by the raw content bytes in colon-separated hex:

SEQUENCE {
  SEQUENCE {
    [0] INTEGER 2
    SEQUENCE {
      OID 1.2.840.113549.1.1.11
      NULL
    }
    SEQUENCE {
      SET {
        SEQUENCE {
          OID 2.5.4.3
          UTF8String "Test CA" [54:65:73:74:20:43:41]
        }
      }
    }
  }
}

The openssl mode produces one line per element with byte offsets:

    0:d= 0 hl= 4 l= 853 cons: SEQUENCE
    4:d= 1 hl= 4 l= 573 cons: SEQUENCE
    8:d= 2 hl= 2 l=   3 cons: cont [ 0 ]
   10:d= 3 hl= 2 l=   1 prim: INTEGER           :02

The hex mode emits space-separated uppercase hex pairs, suitable as input to another asn1parse --inform hex invocation.

Future Commands

Additional commands planned:

• csr - Certificate signing request inspection
• crl - Certificate revocation list inspection
• pkcs7 - PKCS#7 message inspection
• pkcs12 - PKCS#12 keystore inspection
• verify - Certificate chain verification

Development

Build the tool:

cargo build -p synta-tools

Run tests:

cargo test -p synta-tools

Run the tool in development:

cargo run -p synta-tools -- asn1parse <file>