38 lines
1.6 KiB
Markdown
38 lines
1.6 KiB
Markdown
---
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title: Public Key
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description: A simple interface for handling private keys.
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---
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# Public Key
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## Description
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Represents a bitcoin public key and is needed to be able to receive bitcoin, as is usually represented as a bitcoin [Address](address.md), see the official [Bitcoin Wiki](https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses). A PublicKey in Bitcore is an immutable object and can be instantiated from a [Point](crypto.md), string, [PrivateKey](privatekey.md), Buffer and a [BN](crypto.md).
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## Instantiate a Public Key
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Here is how to instantiate a public key:
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```javascript
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var privateKey = new PrivateKey();
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// from a private key
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var publicKey = new PublicKey(privateKey);
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// from a der hex encoded string
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var publicKey2 = new PublicKey('02a1633cafcc01ebfb6d78e39f687a1f0995c62fc95f51ead10a02ee0be551b5dc');
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```
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## Validating a Public Key
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A public key point should be on the [secp256k1](https://en.bitcoin.it/wiki/Secp256k1) curve, instantiating a new PublicKey will validate this and will throw an error if it's invalid. To check that a public key is valid:
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```javascript
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if (PublicKey.isValid('02a1633cafcc01ebfb6d78e39f687a1f0995c62fc95f51ead10a02ee0be551b5dc')){
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// valid public key
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}
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```
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Note: It's important to note that there are two possible ways to represent public key, the standard is *compressed* and includes the x value and parity (as represented above in the documentation). There is also a longer version that is *uncompressed* which includes both x and y values, and using this can generate a different bitcoin address, so it's important to note this possibility, however it's discouraged to be used.
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