PublicKey Tcl Reference Documentation

PublicKey

Current Version: 11.5.0

PublicKey

Load, inspect, convert, export, and use public-key material.

PublicKey represents one public key at a time and provides loading, inspection, and format-conversion operations. It can load keys from many common formats, including DER, PEM, XML, JWK, Base64 DER, RFC 4716 SSH2 blocks, raw ECDSA coordinates, and Ed25519 hex, then export them as DER, PEM, encoded DER, JWK, XML, or files. Public keys are commonly used for signature verification, encryption, JWT/JWS validation, SSH-related workflows, and interoperability with certificates, private keys, and external cryptographic systems.

Load public keys

Import public keys from PEM, DER, XML, JWK, Base64 DER, RFC 4716 SSH2 blocks, raw ECDSA coordinates, or Ed25519 hex.

Export and convert

Convert public keys to DER, PEM, encoded DER, JWK, XML, or file-based output for use by other systems and APIs.

Work with key types

Represent public keys for RSA, DSA, ECDSA, Ed25519, and related public-key cryptographic workflows.

Verify signatures

Pass public keys to Chilkat classes that verify signatures, JWTs, JWS objects, signed data, or protocol-specific authentication messages.

Encrypt or validate data

Use public-key material for operations where the public half of a key pair is required, such as encryption or verification.

Interoperate with certs and keys

Use Cert to obtain a public key from an X.509 certificate, or use PrivateKey to obtain the public portion of an encrypted private key.

Common pattern: Each object holds zero or one key. A successful load replaces the current key, and every failed load clears it. General loaders can accept supported unencrypted private-key representations and retain only their public portion. Direct X.509 certificate input and encrypted private-key input are not supported. Load certificates with Cert, and load encrypted private keys with PrivateKey, then obtain the public key from those objects.

Object Creation

# 'this' is not a keyword in Tcl. It can freely be used as a variable name.
set this [new CkPublicKey]

Properties

DebugLogFilePath
string
# ckStr is a CkString
CkPublicKey_get_DebugLogFilePath $this $ckStr
set strVal [CkPublicKey_get_debugLogFilePath $this]
CkPublicKey_put_DebugLogFilePath $this $strVal

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

  • A timeout property set to 0, indicating an infinite timeout.
  • A hang occurring within an event callback in the application code.
  • An internal bug in the Chilkat code causing the hang.

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Empty
boolean 1/0
set boolVal [CkPublicKey_get_Empty $this]
Introduced in version 9.5.0.87

Returns 1 if no public key is currently loaded, and 0 if this object contains a public key. A newly constructed PublicKey object is empty.

A PublicKey object holds at most one key. Every successful load replaces the current key. Every failed load clears the object; a previously loaded key is never preserved after a load failure.

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KeySize
integer
set intVal [CkPublicKey_get_KeySize $this]
Introduced in version 9.5.0.67

Returns the key size in bits. The meaning is algorithm-specific:

Key typeReported size
RSAThe bit length of the RSA modulus, such as 2048.
DSAThe bit length of the prime parameter p.
ECThe size of the curve field, such as 256 for P-256.
Ed25519256.
Empty object0.
Security strength: Key sizes are not directly comparable across algorithms. For example, a 256-bit EC key and a 2048-bit RSA key have different encodings and security characteristics.

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KeyType
string
# ckStr is a CkString
CkPublicKey_get_KeyType $this $ckStr
set strVal [CkPublicKey_get_keyType $this]
Introduced in version 9.5.0.52

Returns the type of public key currently held by this object.

ValueMeaning
emptyNo public key is loaded.
rsaAn RSA public key.
dsaA DSA public key.
eccAn elliptic-curve public key, commonly used with ECDSA or ECDH.
ed25519An Ed25519 public key.
Key type versus key format: The key type identifies the cryptographic algorithm. DER, PEM, JWK, and XML are representations of the same key material, not additional key types. X25519 keys are not supported by this class.

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LastErrorHtml
string
# ckStr is a CkString
CkPublicKey_get_LastErrorHtml $this $ckStr
set strVal [CkPublicKey_get_lastErrorHtml $this]

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorText
string
# ckStr is a CkString
CkPublicKey_get_LastErrorText $this $ckStr
set strVal [CkPublicKey_get_lastErrorText $this]

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorXml
string
# ckStr is a CkString
CkPublicKey_get_LastErrorXml $this $ckStr
set strVal [CkPublicKey_get_lastErrorXml $this]

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastMethodSuccess
boolean 1/0
set boolVal [CkPublicKey_get_LastMethodSuccess $this]
CkPublicKey_put_LastMethodSuccess $this $boolVal

Indicates the success or failure of the most recent method call: 1 means success, 0 means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.

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Utf8
boolean 1/0
set boolVal [CkPublicKey_get_Utf8 $this]
CkPublicKey_put_Utf8 $this $boolVal

When set to 1, all string arguments and return values are interpreted as UTF-8 strings. When set to 0, they are interpreted as ANSI strings.

In Chilkat v11.0.0 and later, the default value is 1. Before v11.0.0, it was 0.

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VerboseLogging
boolean 1/0
set boolVal [CkPublicKey_get_VerboseLogging $this]
CkPublicKey_put_VerboseLogging $this $boolVal

If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
string
# ckStr is a CkString
CkPublicKey_get_Version $this $ckStr
set strVal [CkPublicKey_get_version $this]

Version of the component/library, such as "10.1.0"

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Methods

GetDerBd
# preferPkcs1 is a boolean
# bd is a CkBinData
set status [CkPublicKey_GetDerBd $this $preferPkcs1 $bd]
Introduced in version 11.0.0

Writes the public key as binary DER to bd. preferPkcs1 selects the representation using the same RSA, EC, DSA, and Ed25519 rules described for GetDer.

bd is replaced; data already present in the BinData is not appended to. If the method fails, including when this object is empty, bd is cleared.

Preferred binary export: Use this method instead of the legacy byte-array-returning GetDer when working with binary data in newer code.

Returns 1 for success, 0 for failure.

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GetEncoded
# preferPkcs1 is a boolean
# encoding is a string
# outStr is a CkString (output)
set status [CkPublicKey_GetEncoded $this $preferPkcs1 $encoding $outStr]
set retStr [CkPublicKey_getEncoded $this $preferPkcs1 $encoding]
Introduced in version 9.5.0.58

Returns the DER representation selected by preferPkcs1, encoded as text using the binary encoding named by encoding. The DER-selection rules are the same as for GetDer.

Common encoding valueOutput encoding
base64Standard Base64 with no line breaks. This is the most common choice for textual DER.
base64UrlURL-safe Base64, useful when key bytes must appear in URLs or JSON-oriented protocols.
hexUppercase hexadecimal.
hexLowerLowercase hexadecimal.

Encoding names are case-insensitive. See the Chilkat Binary Encoding List for the complete set of supported encoding names. An empty or unsupported encoding name causes the method to fail. The method also fails if this object is empty.

Returns 1 for success, 0 for failure.

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GetJwk
# outStr is a CkString (output)
set status [CkPublicKey_GetJwk $this $outStr]
set retStr [CkPublicKey_getJwk $this]
Introduced in version 9.5.0.66

Returns the public key as a compact JWK (JSON Web Key). Binary values use Base64url encoding without padding. Repeated calls for the same key produce the same compact member order.

RSA:

{"kty":"RSA","n":"BASE64URL_MODULUS","e":"BASE64URL_EXPONENT"}

EC:

{"kty":"EC","crv":"P-256","x":"BASE64URL_X","y":"BASE64URL_Y"}

Ed25519:

{"kty":"OKP","crv":"Ed25519","x":"BASE64URL_PUBLIC_KEY"}

Only public key parameters are emitted. Private members and optional JWK metadata are not included. The method fails if this object is empty or if the loaded key type cannot be represented as a supported JWK.

RSA exponent: The value AQAB commonly represents exponent 65537, but the actual exponent from the loaded RSA key is exported.

Returns 1 for success, 0 for failure.

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GetJwkThumbprint
# hashAlg is a string
# outStr is a CkString (output)
set status [CkPublicKey_GetJwkThumbprint $this $hashAlg $outStr]
set retStr [CkPublicKey_getJwkThumbprint $this $hashAlg]
Introduced in version 9.5.0.66

Returns the RFC 7638 JWK thumbprint for this public key. Chilkat constructs the required canonical JSON object from the public JWK members, hashes its UTF-8 representation using the algorithm named by hashAlg, and returns the digest using Base64url encoding without padding.

Accepted algorithm names are md5, sha1, sha256, sha384, and sha512. Names are case-insensitive. An empty or unsupported algorithm name causes the method to fail. sha256 is the conventional choice for RFC 7638 thumbprints.

The method fails if this object is empty or if the key cannot be represented as a supported JWK.

Not a certificate thumbprint: A JWK thumbprint identifies public key parameters. An X.509 certificate fingerprint hashes the complete DER-encoded certificate and is therefore a different value.

Returns 1 for success, 0 for failure.

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GetPem
# preferPkcs1 is a boolean
# outStr is a CkString (output)
set status [CkPublicKey_GetPem $this $preferPkcs1 $outStr]
set retStr [CkPublicKey_getPem $this $preferPkcs1]
Introduced in version 9.5.0.58

Returns the public key in PEM format. preferPkcs1 selects the underlying DER representation as follows:

Key typepreferPkcs1 = 1preferPkcs1 = 0
RSARSA PUBLIC KEY, containing PKCS #1 RSAPublicKey.PUBLIC KEY, containing X.509 SubjectPublicKeyInfo.
ECPUBLIC KEY with named-curve parameters.PUBLIC KEY with explicit EC domain parameters.
Ed25519PUBLIC KEY.The same PUBLIC KEY representation.

PEM output uses CRLF line endings, Base64 body lines of at most 64 characters, and a final CRLF after the closing boundary line. The method fails if this object is empty.

PEM is DER plus text armor: The Base64 body contains the DER representation selected by preferPkcs1. The boundary label identifies the enclosed structure.

Returns 1 for success, 0 for failure.

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GetXml
# outStr is a CkString (output)
set status [CkPublicKey_GetXml $this $outStr]
set retStr [CkPublicKey_getXml $this]

Returns the public key in Chilkat XML format. The exact representation depends on the key type.

RSA:

<RSAPublicKey><Modulus>BASE64_MODULUS</Modulus><Exponent>BASE64_EXPONENT</Exponent></RSAPublicKey>

DSA:

<DSAPublicKey>
  <P>BASE64_P</P>
  <Q>BASE64_Q</Q>
  <G>BASE64_G</G>
  <Y>BASE64_Y</Y>
</DSAPublicKey>

EC:

<ECCPublicKey curve="secp256r1" x="UPPERCASE_HEX_X" y="UPPERCASE_HEX_Y">BASE64_DER</ECCPublicKey>

For EC keys, the curve attribute contains the Chilkat curve name, the x and y attributes contain full-width uppercase hexadecimal coordinates, and the element text contains a Base64-encoded DER public-key structure with explicit curve parameters.

Ed25519:

<Ed25519PublicKey>BASE64_32_BYTE_PUBLIC_KEY</Ed25519PublicKey>

The returned XML can be loaded by LoadFromString, LoadFromFile, or LoadBd. The method fails if this object is empty.

Interoperability note: These XML forms are Chilkat representations. For interchange with non-Chilkat systems, PEM, DER, or JWK is usually preferable.

Returns 1 for success, 0 for failure.

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LoadBase64
# keyStr is a string
set status [CkPublicKey_LoadBase64 $this $keyStr]
Introduced in version 9.5.0.47

Loads a public key from standard Base64-encoded DER in keyStr. Whitespace within the Base64 text is permitted. The decoded DER is inspected to determine the key type and structure. For RSA, both PKCS #1 RSAPublicKey and X.509 SubjectPublicKeyInfo are recognized.

A complete PEM string is also accepted, including its BEGIN/END boundary lines. Base64url text, arbitrary non-PEM text surrounding the encoded data, X.509 certificates, and encrypted private keys are not accepted.

A successful load replaces the current key. A failed load clears this object.

Certificates and encrypted private keys: Direct X.509 certificate input is not supported. Load a certificate with a Cert object and obtain its public key from the certificate. Encrypted private-key input is also not supported by this class; load and decrypt it with a PrivateKey object, then obtain the corresponding public key.
DER terminology: The general X.509 public-key wrapper is SubjectPublicKeyInfo. It is sometimes informally called a “PKCS #8 public key,” although PKCS #8 formally defines private-key syntax.

Returns 1 for success, 0 for failure.

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LoadBd
# bd is a CkBinData
set status [CkPublicKey_LoadBd $this $bd]
Introduced in version 9.5.0.83

Loads a public key from the data in bd. The BinData may contain binary DER or any textual representation recognized by LoadFromString, including PEM, Chilkat XML, JWK, standard Base64 DER, and supported RFC 4716 SSH2 public-key blocks.

Public keys and unencrypted private keys are accepted; when private-key material is supplied, only the public portion is retained. For binary DER, the first recognized DER object is loaded and trailing bytes are ignored. Hex-encoded DER, Base64url-encoded DER, one-line OpenSSH public keys, X.509 certificates, and encrypted private keys are not recognized.

JWK required-member and metadata behavior is the same as described for LoadFromString. A successful load replaces the current key. A failed load clears this object.

Certificates and encrypted private keys: Direct X.509 certificate input is not supported. Load a certificate with a Cert object and obtain its public key from the certificate. Encrypted private-key input is also not supported by this class; load and decrypt it with a PrivateKey object, then obtain the corresponding public key.
Recommended general-purpose loader: Use this method when the key data may be binary or text, or when the precise representation is not known in advance.

Returns 1 for success, 0 for failure.

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LoadEcdsa
# curveName is a string
# Qx is a string
# Qy is a string
set status [CkPublicKey_LoadEcdsa $this $curveName $Qx $Qy]
Introduced in version 9.5.0.85

Loads an elliptic-curve public key directly from its affine point coordinates. curveName names the curve, Qx is the hexadecimal x-coordinate (Qx), and Qy is the hexadecimal y-coordinate (Qy).

The coordinate strings must contain exactly the full field width for the selected curve. Uppercase and lowercase hexadecimal are accepted. A 0x prefix, whitespace, separators, extra leading zero bytes, shortened coordinates, non-hexadecimal characters, empty values, and all-zero coordinates are rejected. Curve names are case-insensitive.

Supported curveDescription and aliases
secp256r1NIST P-256; also known as P-256 and prime256v1.
secp384r1NIST P-384; also known as P-384.
secp521r1NIST P-521; also known as P-521.
secp256k1The 256-bit Koblitz curve used by Bitcoin.
secp192r1192-bit SEC/NIST curve.
secp224r1224-bit SEC/NIST curve.
brainpoolP160r1160-bit Brainpool curve.
brainpoolP192r1192-bit Brainpool curve.
brainpoolP224r1224-bit Brainpool curve.
brainpoolP256r1256-bit Brainpool curve.
brainpoolP320r1320-bit Brainpool curve.
brainpoolP384r1384-bit Brainpool curve.
brainpoolP512r1512-bit Brainpool curve.

A successful load replaces the current key. A failed load clears this object. The method validates syntax, coordinate width, and obvious zero values, but it does not fully verify that the supplied coordinates form a point on the named curve.

Raw coordinates versus encoded keys: Use this method only when the curve name and separate x/y coordinates are already available. For DER, PEM, JWK, XML, or other complete key representations, use LoadBd, LoadFromString, or LoadFromFile.

Returns 1 for success, 0 for failure.

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LoadEd25519
# pubKey is a string
set status [CkPublicKey_LoadEd25519 $this $pubKey]
Introduced in version 9.5.0.83

Loads a raw Ed25519 public key from the hexadecimal string in pubKey. pubKey must contain exactly 64 hexadecimal characters representing 32 bytes. Uppercase and lowercase hexadecimal are accepted.

A 0x prefix, whitespace, separators, non-hexadecimal characters, odd-length input, and values shorter or longer than 32 bytes are rejected. A successful load replaces the current key; a failed load clears this object.

This method validates the hexadecimal syntax and exact byte count. It does not determine whether every 32-byte value is a usable Ed25519 public point; for example, an all-zero 32-byte value is accepted.

Ed25519 is not X25519: Ed25519 is a signature system and X25519 is a key-agreement system. Their public keys are not interchangeable, and X25519 keys are not supported by this class.

Returns 1 for success, 0 for failure.

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LoadFromFile
# path is a string
set status [CkPublicKey_LoadFromFile $this $path]
Introduced in version 9.5.0.58

Loads a public key from the local filesystem path specified by path. Chilkat examines the file contents rather than the filename extension. Supported content includes binary DER, PEM, Chilkat XML, JWK, standard Base64 DER, and RFC 4716 SSH2 public-key blocks for supported RSA and Ed25519 keys.

Public keys and unencrypted private keys are accepted. When private-key material is supplied, only the public portion is retained. Hex-encoded DER, Base64url-encoded DER, one-line OpenSSH public keys, X.509 certificates, and encrypted private keys are not recognized.

For PEM files, UTF-8 BOMs, CRLF or LF line endings, surrounding text, and unrelated PEM blocks are tolerated. If multiple recognized key blocks are present, the first recognized key is loaded. For binary DER, the first recognized DER object is loaded and trailing bytes are ignored.

JWK required-member and metadata behavior is the same as described for LoadFromString. A successful load replaces the current key. A failed load clears this object.

Certificates and encrypted private keys: Direct X.509 certificate input is not supported. Load a certificate with a Cert object and obtain its public key from the certificate. Encrypted private-key input is also not supported by this class; load and decrypt it with a PrivateKey object, then obtain the corresponding public key.

Returns 1 for success, 0 for failure.

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LoadFromString
# keyString is a string
set status [CkPublicKey_LoadFromString $this $keyString]
Introduced in version 9.5.0.58

Loads a public key from the string in keyString. Chilkat examines the content and recognizes these textual representations:

  • PEM public keys.
  • Unencrypted PEM private keys, from which only the public portion is retained.
  • Chilkat XML public or private keys.
  • Public or private JWK.
  • Standard Base64-encoded DER.
  • RFC 4716 SSH2 public-key blocks for supported RSA and Ed25519 keys.

Hex-encoded DER, Base64url-encoded DER, one-line OpenSSH forms such as ssh-rsa ... and ssh-ed25519 ..., X.509 certificates, and encrypted private keys are not recognized.

For PEM input, UTF-8 BOMs, CRLF or LF line endings, leading and trailing whitespace, unrelated surrounding text, and unrelated PEM blocks are tolerated. If multiple recognized key blocks are present, the first recognized key is loaded.

For JWK input, required public members must be present. Private members such as d may be present but are discarded. Optional metadata such as kid, use, alg, key_ops, and x5c is not retained.

Key typeRequired public members
RSAkty, n, and a nonzero e.
ECkty, crv, x, and y.
Ed25519kty, crv, and x.

A successful load replaces the current key. A failed load clears this object.

Certificates and encrypted private keys: Direct X.509 certificate input is not supported. Load a certificate with a Cert object and obtain its public key from the certificate. Encrypted private-key input is also not supported by this class; load and decrypt it with a PrivateKey object, then obtain the corresponding public key.
Validation scope: JWK loading validates the required structure and basic values, but it does not prove that supplied EC or Ed25519 public bytes are mathematically valid or trusted.

Returns 1 for success, 0 for failure.

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SaveDerFile
# preferPkcs1 is a boolean
# path is a string
set status [CkPublicKey_SaveDerFile $this $preferPkcs1 $path]
Introduced in version 9.5.0.58

Saves the public key to path as binary DER. preferPkcs1 selects the representation using the same RSA, EC, and Ed25519 rules described for GetDer.

An existing destination file is overwritten. Parent directories are not created automatically. The method fails if path names a directory. If this object is empty, the method fails without creating the file.

Windows read-only files: An existing read-only destination may be replaced; the resulting file is not left with the read-only attribute.

Returns 1 for success, 0 for failure.

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SavePemFile
# preferPkcs1 is a boolean
# path is a string
set status [CkPublicKey_SavePemFile $this $preferPkcs1 $path]
Introduced in version 9.5.0.58

Saves the public key to path in PEM format. preferPkcs1 selects the representation and PEM label using the same rules described for GetPem.

The generated file uses CRLF line endings, Base64 body lines of at most 64 characters, and a final CRLF. An existing destination file is overwritten. If this object is empty, the method fails without creating the file.

Returns 1 for success, 0 for failure.

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SaveXmlFile
# path is a string
set status [CkPublicKey_SaveXmlFile $this $path]

Saves the public key to the local filesystem path specified by path using exactly the same key-type-specific XML text returned by GetXml. No additional BOM or line ending is added.

An existing destination file is overwritten. If this object is empty, the method fails without creating the destination file.

Choosing a file format: Use XML when another Chilkat application will read the key. For broader interoperability, PEM or DER is usually a better choice.

Returns 1 for success, 0 for failure.

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Deprecated

GetDer Deprecated
# preferPkcs1 is a boolean
# outBytes is a CkByteData (output)
set status [CkPublicKey_GetDer $this $preferPkcs1 $outData]
Introduced in version 9.5.0.58

Returns the public key as binary DER. preferPkcs1 is a historical format-preference flag whose exact effect depends on the key type:

Key typepreferPkcs1 = 1preferPkcs1 = 0
RSAPKCS #1 RSAPublicKey containing the modulus and exponent.X.509 SubjectPublicKeyInfo using the RSA OID 1.2.840.113549.1.1.1.
ECX.509 SubjectPublicKeyInfo using a named-curve OID.X.509 SubjectPublicKeyInfo containing explicit EC domain parameters.
Ed25519X.509 SubjectPublicKeyInfo using OID 1.3.101.112.The same Ed25519 SubjectPublicKeyInfo representation.

For DSA, Chilkat returns its supported DSA DER representation. The method fails if this object is empty.

EC behavior: For EC keys, preferPkcs1 does not select PKCS #1. It selects the concise named-curve encoding when 1 and the larger explicit-parameter encoding when 0.

Returns 1 for success, 0 for failure.

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LoadFromBinary Deprecated
# keyBytes is a CkByteData
set status [CkPublicKey_LoadFromBinary $this $keyBytes]
Introduced in version 9.5.0.58

Loads a public key from binary DER in keyBytes. The DER structure and key type are detected automatically. Public-key DER and unencrypted private-key DER are accepted; when private-key material is supplied, only the public portion is retained.

For RSA, both PKCS #1 RSAPublicKey and X.509 SubjectPublicKeyInfo are recognized. The loader parses the first recognized DER object and ignores trailing bytes, including a second concatenated DER object.

A successful load replaces the current key. A failed load clears this object.

Certificates and encrypted private keys: Direct X.509 certificate input is not supported. Load a certificate with a Cert object and obtain its public key from the certificate. Encrypted private-key input is also not supported by this class; load and decrypt it with a PrivateKey object, then obtain the corresponding public key.
Preferred API: This byte-array method is retained for compatibility. New applications should generally place the data in a BinData object and call LoadBd.

Returns 1 for success, 0 for failure.

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