Pem envelope format

pem-envelope-format · version 1.0.0 · Encoding & checksums · free, no key needed

Format a label and lowercase hex bytes as a canonical RFC 7468 PEM envelope.

Use when you need to: format hex bytes as a pem envelope · wrap raw bytes in pem begin and end lines · canonical 64 column pem rendering.

Decide before calling

Read the versioned contract and the supported scope below. Reuse pem-envelope-format@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use pem-envelope-format@1.0.0 for format hex bytes as a pem envelope. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• format hex bytes as a pem envelope
• wrap raw bytes in pem begin and end lines
• canonical 64 column pem rendering
• build an rfc 7468 textual message
• encode bytes as pem armor
• render a strict pem block from a label and hex

Not supported

• choose the label by inspecting the bytes
• wrap base64 at a width other than 64
• add openssl explanatory text around the block
• encrypt or sign the payload

Behavior

• Output is Figure 3: "-----BEGIN ", the label, "-----", a newline, base64 wrapped at exactly 64 characters (the final line holds the remainder, and a full final line of 64 is kept), then "-----END ", the same label, "-----", and a newline. No trailing blanks and no blank line are emitted.
• bytes_hex is lowercase even-length hexadecimal with no prefix or whitespace. Omitted eol means LF. eol "crlf" uses CRLF. CR-only is accepted by the parser and is not generated.
• The label is the RFC 7468 section 3 ABNF, case-sensitive, empty allowed, at most 64 bytes. The byte limit is checked before grammar, so a longer label is limit_exceeded even when it would also fail the grammar. This bound is an implementation limit; the RFC ABNF has none.
• Empty bytes produce a block with no base64 line. The bytes are wrapped as opaque data and are not checked for being a key, certificate, or any ASN.1 type.
• A hex string longer than 6144 characters (3072 bytes) is limit_exceeded before alphabet checks. The JSON result is capped at 8192 UTF-8 bytes.
• Disclaimer: format transform only; provides no confidentiality, integrity, or authenticity.

Input

• label (string, required): min length 0; max length 64; pattern ^(?:[\x21-\x2C\x2E-\x7E](?:[ \x2D]?[\x21-\x2C\x2E-\x7E])*)?$
• bytes_hex (string, required): min length 0; max length 6144; pattern ^(?:[0-9a-f]{2})*$
• eol (one of "lf", "crlf", optional)

Output

• text (string, required): min length 1; max length 8192

Limits

• max label bytes: 64
• max hex chars: 6144
• max output bytes: 8192

Example

Request input:

{
  "label": "EXAMPLE",
  "bytes_hex": "00"
}

Response:

{
  "result": {
    "text": "-----BEGIN EXAMPLE-----\nAA==\n-----END EXAMPLE-----\n"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "pem-envelope-format",
  "version": "1.0.0",
  "input": {
    "label": "EXAMPLE",
    "bytes_hex": "00"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/pem-envelope-format/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"label":"EXAMPLE","bytes_hex":"00"}'

The machine-readable contract is at /v1/tools/pem-envelope-format/versions/1.0.0.

CLI

node cli.mjs run pem-envelope-format 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Pem envelope parse: Parse one RFC 7468 textual envelope into its label and lowercase hex bytes.
• Pem envelope validate: Check one RFC 7468 PEM envelope for labels, whitespace, and strict base64.
• Pem label validate: Check a PEM label against the RFC 7468 label grammar, without reading a payload.
• Bech32 encode: Encode lowercase HRP and 5-bit data as Bech32 or Bech32m text using that checksum.
• Ct merkle root compute: Compute the RFC 6962 v1 domain-separated Merkle Tree Hash of raw leaves.
• Asn1 oid format: Format numeric object identifier arcs as dotted text or brace notation.