A simple low-level ANSI/NIST-ITL 1-2011 (update 2015) encoding and decoding utility library. Written in Typescript for Node.
Install package
npm install --save node-nistEncoding and decoding are described separately but they share many concepts.
In particular, nistEncode and nistDecode return a result (they do not throw exceptions).
A Result is a TypeScript discriminated union where a Success is tagged with tag === 'success
and a Failure with tag === 'failure.
In fact, Result is very similar to Either monad known from functional programming languages.
nistEncode and nistDecode could work on the NIST object alone. But they work best when codec
options are specific as their second argument. This way you can specify default values and impose
validation checks on individual NIST fields.
- Encode a simple NIST object containing only Type-1 and Type-2 records:
import { nistEncode, NistFile } from 'node-nist';
const nist: NistFile = {
1: {
2: '0502', // version
4: 'CRM', // TOT
5: '20190717', // date
7: 'DAI035454', // DAI
8: 'ORI38574354', // ORI
9: 'TCN2487S054' // TCN
},
2: {
4: 'John',
5: 'Doe',
7: '1978-05-12'
}
};
const encodeResult = nistEncode(nist, {});
if (encodeResult.tag === 'success') {
const buffer = encodeResult.value;
// perform action on successfull encode, such as sending out the buffer
} else {
const error = encodeResult.error;
// perform action on unsuccessfull encode, such as logging an error
}- Encode a NIST object with a different set of Type-2 record fields, containing also two fingerprints:
import { nistEncode, NistFile } from 'node-nist';
const nist: NistFile = {
1: {
2: '0300', // version
4: 'IDN', // TOT
5: '20190722', // date
7: 'ABIS', // DAI
8: 'MID00001', // ORI
9: 'SEN20190722093422-IDE-00040' // TCN
},
2: {
901: 'MID00001'
},
4: [
{
3: '0', // flat finger
4: ['7'], // left index finger
9: 'fingerprint binary data'
},
{
3: '0', // flat finger
4: ['2'], // right index finger
9: 'fingerprint binary data'
}
]
};
const encodeResult = nistEncode(nist, {});
if (encodeResult.tag === 'success') {
const buffer = encodeResult.value;
// perform action on successfull encode, such as sending out the buffer
} else {
const error = encodeResult.error;
// perform action on unsuccessfull encode, such as logging an error
}- Encode a NIST object containing two fingerprints. Specify also NistEncodeOptions which are used to automatically populate default values and to check whether the input NIST object conforms to all the validation rules.
import { nistEncode, NistEncodeOptions, NistFile } from 'node-nist';
const nistEncodeOptions: NistEncodeOptions = {
codecOptions: {
MAP: { // TOT-specific encode options
1: {
6: {
defaultValue: '5',
mandatory: true,
regexs: [{ regex: '^[1-9]{1}$', errMsg: 'Expected a number between 1 and 9' }]
}
}
},
default: {
1: {
2 /* ver */: {
defaultValue: '0502', // conforming to ANSI/NIST-ITL 1-2011 edition 3 update 2015
formatter: (field: NistField) => String(field.value).padStart(4, '0'),
mandatory: true,
maxLength: 4,
minLength: 3,
regexs: [{ regex: '^[0-9]{3,4}$', errMsg: 'Expected three or four digits' }]
},
4 /* tot */: {
mandatory: true,
maxLength: 16
},
5 /* dat */: {
mandatory: true,
regexs: [{ regex: '^[0-9]{8}$', errMsg: 'Expected eight digits' }]
},
6 /* pry */: {
mandatory: false,
regexs: [{ regex: '^[1-9]{1}$', errMsg: 'Expected a number between 1 and 9' }]
},
7 /* dai */: {
mandatory: true
},
8 /* ori */: {
mandatory: true
},
9 /* tcn */: {
mandatory: true
},
10 /* tcr */: {
mandatory: false
},
11 /* nsr */: {
defaultValue: (field: NistField, nist: NistFile) => getFingerprintResolution(nist),
mandatory: true,
regexs: [{ regex: '^[0-9]{2}.[0-9]{2}$', errMsg: 'Expected a string in format dd.dd' }]
},
12 /* ntr */: {
defaultValue: (field: NistField, nist: NistFile) => getFingerprintResolution(nist),
mandatory: true,
regexs: [{ regex: '^[0-9]{2}.[0-9]{2}$', errMsg: 'Expected a string in format dd.dd' }]
}
},
4: {
3 /* imp */: {
mandatory: true
},
4 /* fgp */: {
mandatory: true
},
5 /* isr */: {
defaultValue: '0', // 500 ppi
mandatory: true
},
6 /* hll */: {
defaultValue: () => getHorizontalScanningLine(),
mandatory: true
},
7 /* vll */: {
defaultValue: () => getVerticalScanningLine(),
mandatory: true
},
8 /* cga */: {
defaultValue: '1', // WSQ
mandatory: true
}
}
}
}
};
const nist: NistFile = {
1: {
2: '0300', // version
4: 'MAP', // TOT
5: '20190722', // date
7: 'ABIS', // DAI
8: 'MID00001', // ORI
9: 'SEN20190722093422-IDE-00040' // TCN
},
2: {
901: 'MID00001'
},
4: [
{
3: '0', // flat finger
4: ['7'], // left index finger
9: 'fingerprint binary data'
},
{
3: '0', // flat finger
4: ['2'], // right index finger
9: 'fingerprint binary data'
}
]
};
const encodeResult = nistEncode(nist, {});
if (encodeResult.tag === 'success') {
const buffer = encodeResult.value;
// perform action on successfull encode, such as sending out the buffer
} else {
const error = encodeResult.error;
// perform action on unsuccessfull encode, such as logging an error
}- Traditional (binary) encoding is used; NIEM-conformant (XML) is not supported.
- Supported records: Type-1, Type-2, Type-4, Type-9, Type-10, Type-13, Type-14.
- Only one Type-2 record is supported.
- Information designation character (IDC) is automatically generated during encoding (linking of records is not supported).
- All Type-1 fields must be 7-bit ASCII.
- Only UTF-8 is supported for other record types.
- Only one Friction ridge generalized position (FGP, 4.004) is supported per one Type-4 record.
- Limit of the encoded NIST file length is 1 GB.
- Limit of the encoded NIST file length is 4 GB, as given by a size of one single Node Buffer.