Creating and managing keys is an important part of the cryptographic process. Symmetric algorithms require the creation of a key and an initialization vector (IV). The key must be kept secret from anyone who should not decrypt your data. The IV does not have to be secret, but should be changed for each session. Asymmetric algorithms require the creation of a public key and a private key. The public key can be made public to anyone, while the private key must known only by the party who will decrypt the data encrypted with the public key. This section describes how to generate and manage keys for both symmetric and asymmetric algorithms.
A crypto key, if you have the.correct. key, can verify for you that the data hasn't been tampered with. The problem is, however, that before you can begin encrypted communications, you must do an.unencrypted. key exchange, where the server gives you it's crypto key. Here's where the man-in-the-middle has an opportunity. Use the generateKey method of the SubtleCrypto interface to generate a new key (for symmetric algorithms) or key pair (for public-key algorithms).
The symmetric encryption classes supplied by the .NET Framework require a key and a new initialization vector (IV) to encrypt and decrypt data. Whenever you create a new instance of one of the managed symmetric cryptographic classes using the parameterless constructor, a new key and IV are automatically created. Anyone that you allow to decrypt your data must possess the same key and IV and use the same algorithm. Generally, a new key and IV should be created for every session, and neither the key nor IV should be stored for use in a later session.
To communicate a symmetric key and IV to a remote party, you would usually encrypt the symmetric key by using asymmetric encryption. Sending the key across an insecure network without encrypting it is unsafe, because anyone who intercepts the key and IV can then decrypt your data. For more information about exchanging data by using encryption, see Creating a Cryptographic Scheme.
The following example shows the creation of a new instance of the TripleDESCryptoServiceProvider class that implements the TripleDES algorithm.
When the previous code is executed, a new key and IV are generated and placed in the Key and IV properties, respectively.
Sometimes you might need to generate multiple keys. In this situation, you can create a new instance of a class that implements a symmetric algorithm and then create a new key and IV by calling the GenerateKey and GenerateIV methods. The following code example illustrates how to create new keys and IVs after a new instance of the symmetric cryptographic class has been made.
When the previous code is executed, a key and IV are generated when the new instance of TripleDESCryptoServiceProvider is made. Another key and IV are created when the GenerateKey and GenerateIV methods are called.
The .NET Framework provides the RSACryptoServiceProvider and DSACryptoServiceProvider classes for asymmetric encryption. These classes create a public/private key pair when you use the parameterless constructor to create a new instance. Asymmetric keys can be either stored for use in multiple sessions or generated for one session only. While the public key can be made generally available, the private key should be closely guarded.
A public/private key pair is generated whenever a new instance of an asymmetric algorithm class is created. After a new instance of the class is created, the key information can be extracted using one of two methods:
The ToXmlString method, which returns an XML representation of the key information.
The ExportParameters method, which returns an RSAParameters structure that holds the key information.
Both methods accept a Boolean value that indicates whether to return only the public key information or to return both the public-key and the private-key information. An RSACryptoServiceProvider class can be initialized to the value of an RSAParameters structure by using the ImportParameters method.
Asymmetric private keys should never be stored verbatim or in plain text on the local computer. If you need to store a private key, you should use a key container. For more on how to store a private key in a key container, see How to: Store Asymmetric Keys in a Key Container.
The following code example creates a new instance of the RSACryptoServiceProvider class, creating a public/private key pair, and saves the public key information to an RSAParameters structure.
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Use the generateKey()
method of the SubtleCrypto
interface to generate a new key (for symmetric algorithms) or key pair (for public-key algorithms).
HiYou post is interestnig, is there away I can create a privatre key instance via a signature given stiring?I have pub/private keys generated alreadyKeyPairGenerator keyPairGenerator is going to createa key pair, but in my case I alrady have it and then further want to use them for signign.e.g//ecdsaSign.initSign(keyPair.getPrivate);byte pkInfo = '51114cac71a9575bc1b39104d176a39d81bd1a705b9a1ad32efd2222f13e59ad'.getBytes;// PrivateKey pvtKey = DSAPrivateKey. Java generate and saving keys lyrics.
algorithm
is a dictionary object defining the type of key to generate and providing extra algorithm-specific parameters. RsaHashedKeyGenParams
object.EcKeyGenParams
object.HmacKeyGenParams
object.AesKeyGenParams
object.extractable
is a Boolean
indicating whether it will be possible to export the key using SubtleCrypto.exportKey()
or SubtleCrypto.wrapKey()
.keyUsages
 is an Array
indicating what can be done with the newly generated key. Possible values for array elements are: encrypt
: The key may be used to encrypt
messages.decrypt
: The key may be used to decrypt
messages.sign
: The key may be used to sign
messages.verify
: The key may be used to verify
signatures.deriveKey
: The key may be used in deriving a new key
.deriveBits
: The key may be used in deriving bits
.wrapKey
: The key may be used to wrap a key
.unwrapKey
: The key may be used to unwrap a key
.result
is a Promise
that fulfills with a CryptoKey
(for symmetric algorithms) or a CryptoKeyPair
(for public-key algorithms).The promise is rejected when the following exception is encountered:
SyntaxError
CryptoKey
of type secret
or private
but keyUsages
is empty.SyntaxError
CryptoKeyPair
and its privateKey.usages
attribute is empty.This code generates an RSA-OAEP encryption key pair. See the complete code on GitHub.
This code generates an ECDSA signing key pair. See the complete code on GitHub.
This code generates an HMAC signing key. See the complete code on GitHub.
This code generates an AES-GCM encryption key. See the complete code on GitHub.
Specification | Status | Comment |
---|---|---|
Web Cryptography API The definition of 'SubtleCrypto.generateKey()' in that specification. | Recommendation | Initial definition. |
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | Android webview | Chrome for Android | Firefox for Android | Opera for Android | Safari on iOS | Samsung Internet | |
generateKey | ChromeFull support 37 | EdgePartial support12
| FirefoxFull support 34
| IEPartial support11 Notes
| OperaFull support 24 | SafariFull support 7 | WebView AndroidFull support 37 | Chrome AndroidFull support 37 | Firefox AndroidFull support 34
| Opera AndroidFull support 24 | Safari iOSFull support 7 | Samsung Internet AndroidFull support 6.0 |