One SMS. Complete health history. No internet required.
The Problem
In rural sub-Saharan Africa, patients visit multiple clinics with no shared EMR. Paper records get lost. There's no internet for cloud sync. But nearly every patient has a basic phone that can receive SMS.
The solution: After every visit, the patient receives an encrypted SMS containing their complete significant health history — chronic conditions, all abnormal results, allergies, and the latest visit. Store only the latest SMS. That's the entire portable health record.
End-to-End Flow
How a spoken consultation becomes a portable health record
1
Record
Clinician speaks naturally during the consultation
Raw Audio Transcript
"Patient complains of persistent headache for three days. Blood pressure is one forty-eight over ninety-four. Continue amlodipine at ten milligrams once daily and add hydrochlorothiazide twelve point five. She is allergic to penicillin, NSAIDs, and sulfa drugs..."
2
Extract
On-device AI identifies clinical entities from the transcript
Structured Clinical Data
DxI10 — Essential Hypertension
Dx 2E11.9 — Type 2 Diabetes
BP148/94 mmHg
Temp36.9°C
Rx 1Amlodipine 10mg OD
Rx 2Metformin 850mg BD
Rx 3HCTZ 12.5mg OD
AllergyPenicillin, NSAID, Sulfa
3
Aggregate
Combine current visit with all prior health history
Every new SMS replaces the old one — always contains the complete picture.
4
Encode
Compress entire health record into 92 bytes of binary
92-Byte Binary Payload
Current visit (27B)Chronic conditionsAbnormal vitalsNotes + CRC
33:1 compression ratio vs. equivalent JSON
5
Encrypt
AES-256-GCM encryption using patient's phone number as key
Encryption Pipeline
92 bytes→PBKDF2 (100K iter)→AES-256-GCM→120 bytes
KeyPatient phone number (+ optional PIN)
Nonce12-byte random IV
Auth16-byte GCM authentication tag
6
Deliver
Base64 encode and send as a single standard SMS
From: ChartLite
Loading...
160 chars · 1 SMS
One SMS. Complete health record.
The patient keeps only the latest SMS. Any clinician, at any clinic, can decrypt it with just the patient's phone number — no internet, no server, no paper.
What's Inside Each SMS
1
Latest visit (full detail)
5
Chronic conditions max
5
Abnormal vitals max
255
Total visits tracked
Current Visit
Date, provider, facility
Up to 3 diagnoses (ICD-10)
Up to 3 medications with dose + frequency
Vitals: BP, temperature, pulse, weight
Current allergy flags
Follow-up instructions
Accumulated Health History
Chronic conditions — diagnoses seen in 2+ visits
All abnormal vitals — most recent per type, with dates
Cumulative allergies — union across every visit
Total visit count — full care history length
Recovery: Any Clinic, Any Time
Patient shows SMS on their phone
→
Clinician enters patient phone number
→
PBKDF2 derives key 100K iterations
→
AES-256-GCM decrypt
→
Complete health record
No internet. No server. No paper. The patient's phone IS the health record. The phone number is the key. Any clinician, at any clinic, can recover the full picture in seconds.
How Does the SMS Reach the Provider?
The encrypted SMS lives on the patient's phone. When they visit a new clinic, there are several ways to transfer it:
Transfer Methods
1.
Forward SMS — Patient forwards the encrypted SMS to the clinic's phone number. ChartLite auto-detects it from the inbox
2.
Same device — If the clinic phone is also running ChartLite, the SMS is already in the inbox — just select it in the "Recover SMS" screen
What About Same-Facility Visits?
SMS decryption is not needed within the same facility. All patient data is already in the local encrypted database (SQLCipher). The SMS is only needed at new clinics that have never seen this patient before.
SIM Swap / Lost Number?
The original clinic keeps a full copy in the local encrypted database — the SMS is only for portability
If a patient gets a new number, they revisit their clinic to get a fresh SMS encrypted with the new number
The patient's phone number on file is updated at registration
Encryption: Practical Security
The encryption key is the patient's phone number — something they always know, no memorization required.
Default: Phone Number
The SMS is encrypted using the patient's phone number as the key
The clinician asks "what is your phone number?" — a natural question at any clinic
No PIN to remember, no National ID required
Works in every country, with every patient
Already a massive upgrade over paper records (which have zero encryption)
Think of it like paper records. Paper records are completely unprotected — anyone can read them. Phone-number-encrypted SMS is protected against casual access while remaining practical for clinic use.
Shared Phones? Optional PIN
For patients who share a phone with family, ChartLite supports an optional 4-digit PIN chosen by the patient. The encryption key becomes phoneNumber:PIN — even family members who know the number can't decrypt without the PIN.
No PIN (default) — phone number alone. Zero friction, protects against strangers
With PIN — patient chooses a 4-digit PIN at registration. Protects privacy between family members
PIN is optional and patient-initiated, never forced
Clinician asks: "What's your phone number?" then "Did you set a PIN?"
Enhanced: National ID + PIN
For countries requiring stronger consent (e.g., South Africa with National IDs), a third mode uses National ID + PIN. Configurable per country deployment.
Known penicillin allergy · Lives in rural Limpopo, visits multiple clinics
Visit Timeline
Step through each visit to see the SMS health record build up
SMS on Amara's Phone
From: ChartLite Clinic
No visits yet. Click "Next Visit" to begin Amara's story.
What a Clinician Sees After Decrypting
No data yet. Step through visits to build the health record.
Live Recovery Demo
Amara Okafor walks into Polokwane District Hospital — a clinic she has never visited before. She has no paper records. But she has one SMS on her phone from her last visit at a rural clinic 3 weeks ago.
The clinician copies the encrypted SMS into ChartLite and asks Amara for her phone number. Try it:
Demo phone number pre-filled: 0721234567 · Try a wrong number to see decryption fail
Encrypted SMS (on Amara's phone)
From: Tzaneen PHC · 18 Feb 2026
18/02/2026 14:32 · 160 chars · 1 SMS · Encrypted
Decryption failed. The AES-256-GCM authentication tag does not match — wrong phone number.
Why This Matters
AES-256-GCM is an authenticated encryption scheme. If even one digit of the phone number is wrong, the entire decryption fails — you don't get partial or garbled data, you get nothing. Only the correct phone number can unlock the health record.
Try the correct phone number:0721234567
Decrypted successfully. Full health record recovered from a single SMS.
7
Total clinic visits
2
Chronic conditions
3
Abnormal vitals flagged
3
Known allergies
Latest Visit — 18 Feb 2026
Tzaneen Primary Health Care · Dr. Mokoena
Primary Diagnosis
I10 — Essential Hypertension
Secondary
E11.9 — Type 2 Diabetes
Blood Pressure
148/94 mmHg (High)
Temperature
36.9°C
Pulse
82 bpm
Weight
78 kg
Medication 1
Amlodipine 10mg OD
Medication 2
Metformin 850mg BD
Medication 3
Hydrochlorothiazide 12.5mg OD
Follow-up
14 days
Allergies (this visit)
Penicillin
Chronic Conditions
Diagnoses appearing in 2 or more visits, tracked across all clinics
I10 — Essential Hypertension First diagnosed Sep 2025 at Tzaneen PHC
5 of 7 visits
E11.9 — Type 2 Diabetes Mellitus First diagnosed Nov 2025 at Mopani Clinic
3 of 7 visits
Abnormal Vitals History
Most recent abnormal reading for each vital type, with dates
Date
Vital
Reading
Normal Range
Status
18 Feb 2026
Systolic BP
148 mmHg
90 – 139
HIGH
18 Feb 2026
Diastolic BP
94 mmHg
61 – 89
HIGH
22 Dec 2025
Temperature
38.7°C
35.5 – 37.9
FEVER
Known Allergies (Cumulative)
Union of all allergy flags reported across every visit
PenicillinNSAIDSulfa
Penicillin: reported since first visit. NSAID: flagged Dec 2025 (GI reaction). Sulfa: flagged Jan 2026.
What the Clinician Now Knows
Without any internet connection, server lookup, or paper trail — from a single SMS — the new clinician at Polokwane District Hospital can see that:
Amara is a chronic hypertensive patient with BP consistently elevated across 5 visits
She has Type 2 Diabetes diagnosed 3 months ago, on Metformin
Her current BP is 148/94 — still uncontrolled despite Amlodipine 10mg + HCTZ
She had a febrile episode in December (38.7°C), possibly infectious
She is allergic to Penicillin, NSAIDs, and Sulfa drugs — do NOT prescribe amoxicillin, ibuprofen, or cotrimoxazole
She has had 7 clinic visits across multiple facilities, indicating she is actively engaged in care
Follow-up was due 14 days from 18 Feb — she is slightly overdue
Binary Wire Format (92 bytes — fits in 1 SMS)
Each colored cell = one byte. Hover to see the field. This is what travels inside the encrypted SMS.